I made this feat with the ones made by Yuki Akuma in mind.
http://www.giantitp.com/forums/showt...-By-Yuki-Akuma

Lowered the caster level because a lot of sphere casting is infinite and 15 is still pretty good. The spell points and talents are a little lower than the approximate equivalent baseline sphere caster, but I figured with how much you can boost sphere casting with feats it would be ok if the Chameleon is a little under, and with the Mimic Class Feature addition you can make that up a bit for a few encounters if you really need it.

Spherecasting Focus
You have learned to imitate the free flowing magic of sphere casting.
Prerequisites: Aptitude Focus, Knowledge (Arcana, Religion, or Nature) 6 ranks.
Benefit: You gain talents and sphere access as tough you were a spherecaster. Your caster level is one and a half times your Chameleon level. You gain the Casting class feature and one talent per level after first. You gain one spell point per level plus any one mental ability chosen when you apply this aptitude. You may choose a casting tradition each time you apply this aptitude, but must always have the Skilled Caster drawback for something related to deception(Perform: Acting, and Profession: Criminal as examples, Forgery is also added to your list of potential skills for this aptitude).

You may also use Mimic Class Feature to gain Sphere Specialization, a Domain, or Sorcererous Blood as a Sphere Wizard, Cleric, or Sorcerer of your Chameleon level for one round per Chameleon level per use. Limited use per day abilities gained this way do not reset to maximum until you rest. Temporary Spell Points are consumed first.

In addition, you gain a +2 competence bonus to Concentration and Spellcraft checks, and a +2 bonus to Will saving throws. At 5th level, these bonuses improve to +4.
Chameleon Level Caster Level Talents Spell Points
1st 1 2 1
2nd 3 3 2
3rd 4 4 3
4th 6 5 4
5th 7 6 5
6th 9 7 6
7th 10 8 7
8th 12 9 8
9th 13 10 9
10th 15 11 10