I played around with this today and had some success. No, I didn't get flymode working in ABM but I accidentally gained access to ABM's Bevin. Just to see what would happen, I took a clean install of Uru CC, added the flymode patch, then copied the python folder into a clean install of ABM. This definitely screwed up this installation of ABM (the disabled Relto book being the most notable error) but it had the interesting side effect of adding a link to the main entrance of Bevin into my Bevin linking book. So off I went.
ABM's Bevin has no clock or heek table (but you can already see this from the Bahro stone balcony.) The egg room was the same as it was in MOUL (not the easter egg room from To D'ni.) The egg room's door was also functioning without any manipulation of the light garden's lights. The classroom had the posters requesting that you go to Gahreesen to pick up a Ki and had the map leading you to the Bevin book room (where there was no Gahreesen book.) There was also no imager in the classroom. The light garden was non-functional. The "little islands" Relto page was not there. Also missing were the telescope, the beach ball, the fire marbles, the imager near the main link-in, the visitor log imager near the main link-in and the "welcome" sign. There was no water in the fountain (like in Kirel) and the entrance to the auditorium was barricaded (and without flymode I can't see if there was anything different in the auditorium.)
This is what the Nexus looked like . . .

- abm_nexus.JPG (36.87 KiB) Viewed 4111 times
I was hoping for a link to the city, but nope. And without a functioning Relto book, I had to quit the game to get out of there.
Then I had another idea. In ABM the doors in the back of the Kadish Gallery are lit like they would work if I could get to them but the way is blocked by two barricades. I remembered that adding this line
VAR BOOL islmKdshGalleryBlockerVis[1] DEFAULT=0 DEFAULTOPTION=VAULT
to the city.sdl file would remove these barricades in Uru CC. But for some reason it wasn't working in ABM. I'll try it again later with a clean installation of ABM. I was trying this on my screwed up Python swapped installation.
EDIT: I was able to remove the barricades from the ABM Kadish Gallery, but even though the doors are lit they do not work.
My accidental acquisition of a link to Bevin has me wondering, is there a way to simply add the links from Uru CC's Ae'gura and Bevin books to the Relto bookshelf in ABM?
EDIT: Instead of adding links to the Relto bookshelf, is there a way to put the Uru CC Nexus links into the blank ABM Nexus?