Maybe I'm being daft, but wouldn't the best method be to use this uber caster level build to cast a Gate?
You can control anything up to CL X 2 with no problems. (Yeah, right!) Just get some ridiculous outsider to say the word for you?
Quite how many non unique 100 HD+ monsters there are out there is a good question though.
Given the power/cost of the spells, I would have thought a correctly worded wish or miracle should give you a decent sized boost to your caster level for one spell. Albeit totally dependant on GM interpretation?
