The first thing you have to decide is whether you want your bow to be tillered for the normal string nock or the fixed crawl nock, because you can't tiller for both, other than change the tiller back and forth when you switch. Gripping the string at the fixed crawl nock is sort of an exaggerated 3 under grip, so I would guess tillering for it would be an extension of tillering for 3 under. Normally, tillering for 3 under involves changing the tiller in a negative direction; for example, if the tiller for split fingers is + 3/16, the tiller for 3 under might be zero.
I've never tried to tiller a bow for the crawl, but extending the tillering required for 3 under, I suppose the tiller might end up negative. You would test this by shooting a bare shaft at different tillers until you can get level flight at some acceptable nock point, like 3/8 or 1/2". I'm not sure your ILF bow has that range of adjustment, but you can try.
People who regularly string walk clearly are not tuning/tillering at all the positions where they move their fingers, but I guess once they learn how to string walk, they are accurate enough that they don't worry about it.