Search the book all you want. You'll find "Walk to the Water" happens to be very pivotal in the song analysis. You can search songs by title. Practically all the songs referenced, (and where the U2 catalogue is concerned, that's pretty exhaustive), are in the book by title. Several in multiple places. Now if you actually go down the rabbit hole of how I interpolate things, you'll find I was implying that "Walk to the Water" entering into conjunction with this existing situation was probably already a thing (put it this way, writing the book was the very first moment it became one from a literature standpoint, because I'd excluded it since encountering it in 1998). The reason I thought (beyond discovering it in the writing), that it probably was part of "the matrix" was because although the hair/possible live circumstance in Dublin (back in 1987) were wrong (it looked like a heavily imagined set of lyrics), -it happened to have a lot of signifiers that ran very deep. (I'd excluded it and nearly kept it out of the book because of how it was grounded in a time/place/perhaps person in Dublin.) In the book I said its association was signified not by any treatment U2 had given it, but by how this (and a few other U2 interpolations) happened to conjunct with another album, namely PJ Harvey's "Is This Desire?".
-Oddly PJ Harvey's official video for the first single of this album deliberately clips her own lyrics out in a couple places, and the clipped lyrics are all that you will find online as well.... I thought the shift was signified by a very unusual lyric in a very unusual song that (with the video at least) seems to signify an illicitly tinged meeting in a hotel room (like "Walk to the Water" has) -it's the song "A Perfect Day, Elise". -The strange lyric in question is "the water turned her blond hair black". - It so happens that line shifted the hair from the wrong, to the "right" colour, namely that of the book's female protagonist. Anyways this song juxtaposition was analyzed at some considerable depth (this incidentally is part and parcel of the chapter rewrite that Bono never received in the 2011 draft).
-Bono's male character in the song "Walk to the Water" is wryly self referential, with "painted billboards" standing in for lyrics so basic they are slogans. He's the man with the suitcase full of things he doesn't need. (This song analysis is in Chapter 17 mainly -a post revision that also made it into future Chapters, like I said, all you have to do is search the title. Search "suitcase" and "clown" and you'd find out where this self-referentialism went. If you want to know where the plot's concourse went with "Walk to the Water", read Chapter 17, search PJ Harvey's album (her song "A Perfect Day" was rewritten into Chapter 17) and "In a Little While". -That's TMI. If you really want to flip your lid, search "Salome".)
Sorry, that's a rabbit hole. I put it there to point out that Bono's snippet choice may have actually just shifted the song's context so that it meets the actual literary context (by deliberately making it a part in this matrix of apparent acknowledgement of the literature, -which also appears deliberate on his part), -shifting the song into a "correct" juxtaposition in real time. (I spent quite some time on PJ Harvey's album in Bono's draft as well, but I'm thinking this happened on its own (as the integration of "Walk to the Water" as an element was the substance of the post Bono draft editing that was done to the book after he got it), though that was a place in the notes that was particularly heavy on personal interjection.) If you listen to the BBC broadcast, he's asking the song's object to walk with him to the water and meet at the room at the "Royal hotel" (google that theme in the book, water/shore/sea/underwater/universal unconscious sea etc. (the premise begins at "Wild Horses"), -with those searches, especially the "universal unconscious sea", -you'll find the form of its substance). -Where Bono's songwriting is concerned, the song that employs the shore analogy was literally one he wrote/recorded while I appeared outside the studio, that is "Never Let Me Go", which had three other tracks of curious accompaniment on the "Million Dollar Hotel Soundtrack". In terms of how the (dual) theme in the song plays out in the book, you might find yourself a little floored; it's par with the "stars in her eyes" concept as being the substance of the entire book. Basically it was possible Bono deliberately "captured" the real live personal encounter in song by creatively framing it in the analogy of her appearing on the shore/sand, conjuncting this analogy which is framed in the entire book as an interior one both prior and post encounter in a manner which grounded it to her person in the real world, an event which played out in the music with "Dolphins Were Monkeys" by Ian Brown, and "Afraid" and "I Would Be Your Slave" on David Bowie's Heathen. (If your searching a basic song title like "Afraid", you have to search it inside quotes to find the citation in the book.) This was a key pivot that in review I find the book fails to point out. It's literally the point of integration between the interior abstract symbolism that evolves through the entire course of the book, that gets inserted and grounded in the tangible reality by Bono's current and subsequent songwriting that happened when he received the letters at the studio in 1999. To have Bono "just happen" tug out a snippet that "friezes" that context perfectly in the apparent framework of acknowledging the book (the verse snippet choice is precisely this integration of the abstract symbolism with the concrete reality that happened in 1999), is a very, very big deal.
I'd even go so far as to say that this choice of his in the live performance to launch the album that acknowledged the book was the element that succeeded despite, or made this succeed, which is no small thing.