findchild under d20?

[areteas]

Anyone know where I can find documentation on the findchild function under d20? Or maybe could help me translate a PF eval script to a d20-friendly version? I see from other threads findchild exists but I gather it has different syntax under D20.
The script I'm trying to adapt is to create the MM3/Races of Eberron shifter race using ShadowChemosh's modified Shifter race from the PF community package.

~First 450
~because custom class specials test their existence at First/500, they can't run a script before then
~however, we need to find out what type has been selected, so we know which set of abilities to add
~therefore, we make the check from the class, rather than the bloodline, and forward that tag to the hero
if (hero.findchild[RaceAbil,"thingid.raShifting"].field[usrChosen1].ischosen <> 0) then
perform hero.findchild[RaceAbil,"thingid.raShifting"].field[usrChosen1].chosen.forward[Custom.?]
endif

Custom.x tags don't seem to exist in d20 so I imagine that has to be replaced with User.? at the end there.
However I can't figure out how to fix the findchild part. The raShifting custom ability has a pick field that specifies what type of shifter they are from a list and then sets a tag (i.e. Razorclaw gets User.ShifterRC). The script is designed to look this up. I can't figure out how to put this in a way d20 will accept, though (tried replacing RaceAbil with CustAbil or just Abil, but I'm not even sure it accepts the category,thingid syntax anyway).