As referenced in my comment on the previous post, here is the relevant page where Buddy Baker sees the cave drawings and realizes “a second crisis is coming”:
Animal Man #18, December 1989, page 18
Of course it was drawn vaguely enough that it could represent anything (I think Zero Hour used to be theorized as the future crisis it must have predicted), but now in light of Infinite Crisis I don’t see how the central figure cannot be interpreted as Alex Luthor. And those must be a couple of Flahes with Mercury helmets in that upper pictogram.
Then, of course, the moment when Buddy sees us (in Earth-Prime land?):
Animal Man #19, January 1990, page 11