Hm. No.
I hate to be so blatant, but ithilids are a race that is superior to any
other playable race. Of course, you can find a way to make ithilids
come in par with the rest of the races, but that would be just making
ithilids lame for the sake of making them playable. Its sort of like
playing a dragon.
In other fantasy settings, Ithilids are brain-sucking creatures,
descendants of brain gods. They are best known for their psionic
powers, and the way they create thralls of any other creature.
In 3d eddition, You can play an ithilid, but a 1st level ithilid
psion would be considered to be the same level with a lv 9
human mage. Such an adjustment could never be done in SK.
Instead of ithilid PC's, I would instead suggest to eventualy
create an ithilid area, complete with an elder brain, lots of thralls,
and possibly some connection to the outer planes or the astral.
Though, that would mean they would also need to be given psionic
powers, and that would mean creating a whole new spell list, which
in itself is a lot of trouble.
What I can say is, perhaps if we eventualy see a psion class, there
will also be a mind flayer community area somewhere
