Here's an idea I came up with:
Illithoid racial skill that you can enable called 'psionic coercion'.
Artificially inflates your ego and charisma (for the purposes of influencing), for a constant mana drain.
Possibly improves in power every 5/10 levels after you get it.

Suggestions?

You already have ILLDRAIN. Just grab enough corpses at hand before going to influence, and you should have enough ego.

Charisma makes a lot of difference.
That being said, making illdrain increase Charisma would be good too.

No! illithoid are ugly and smelly things they should have low charisma all the time!

So are merians.

Making Illdrain proportionally raise charisma as your ego increases would be good and certainly not unbalanced.

The Rainbow has spoken.

And anyways, if Illithoids rise on charisma, why not Trills? I mean, with all those feathers and that awesome pic if you signup on Nexus, they're viable to a charisma rise, too.

we (illithoid) can't be both smart, agile, tanky (except when fighting bards), AND charming too. Honestly though, illdrain makes up for a lack of ego just fine. I just accept the fact that I can't be good at everything and therefore must be bad at something-- that being influencing.