Heheheheheheh Oh this thread was asking for me wasn't it?
Primordial GiantEB:SoX Lesser Half GiantCPsi, skip the racial class.
If Dragon is allowed, go Magic-Blooded
Age your self twice.
Sub-Total is: -7 Str, -5 Dex, -3 Con, +6 Int, +0 Wis, +8 Cha.
You'll need to play as a Sorcerer, because you better. Use Incantatrix to Persist spells, or barring knowledge of Errata on DMM a dip into Sacred Exocist. Oh, and those level up points go to Charisma btw.
PrC into Prestigious Bard for one level or get a Runestaff, doesn't matter.
SnowsongFB: +4 Moral to Charisma.
Nixie's GraceSpC: +8 Enhancement to Charisma, also +6 to Dex (saves buying an item) and +2 to Wisdom (meh).
Buy some wands.
Devil's EgoFCI/FCII, forgot: +4 Profane to Charisma.
Righteous AuraSpC: +4 Sacred to Charisma.
Use the gain a Domain's Spells AFC or Feat, doesn't matter.
Greater Visage Of The DeitySpC: +4 Str, +4 Dex, +2 Con, +4 Int, +2 Cha.
Think I'm done yet? Hells no, that was just spells. Let's see what gold can do for you.
Tome of Leadership and InfluenceCore: +5 Inherent to Charisma, normally rounds out that +5 from leveling too.
Horseshoes of FlameSS: +6 Untyped to Charisma baby, also +10 to Int and +2 Dex.
CommandDotF: The word "command" keeps getting reprinted, this is the only +2 one so bite me. +4 Competence to Charisma!
Swim though a Worm of MinousFCII for +1 to your highest ability score, Charisma I'm sure. It's a Magical Location so you "pay" for it.
Brake a deal with a devilFCII? for +1 to Charisma rounding off that odd point from the worm.
Don't forgot drugs. Mertoran Leaf is +2 Alchemical to Charisma for a measly point of Dex damage.
Final Total: -3 Str, +6 Dex, -1 Con, +20 Int, +2 Wis, +54 Cha.
Start with 18 Charisma and you'll be packing 72 at the end of things. +31 to spell save DCs and more spells per day than you have time to cast. And no CL loss for doing it. Hell, you're an Incantatrix, there isn't a more powerful PrC printed. And you can still pick up enough Coldcasting flavored feats for another +6~+8 to Save DCs, +3 damage per die, and +3 to caster level. What more could you ask for?