Psionicsand Spell questions

[The Winter King]

What ways can a spellcaster use psionic powers? Is there some reverse engineered Spell to power concept somewhere? I ask only because my google fu failed.

Also is there a greater shrink item spell? because affecting an item of 2ft^3 per level is kinda...lame.

[Starbuck_II]

What ways can a spellcaster use psionic powers? Is there some reverse engineered Spell to power concept somewhere? I ask only because my google fu failed.

Also is there a greater shrink item spell? because affecting an item of 2ft^3 per level is kinda...lame.

There are spells that produce psionics (back of Expanded Psionics handbook).
http://www.d20srd.org/srd/psionic/spells/overview.htm

But no, other than that above there are no spellcasters that can manifest psionics.

[Tyger]

IN regard to the first question, only if you have a race or class that lets you use psionic powers... so a Wizard 5 / Psion 5 would have access to both. In fact, there is a prestige class (I am not recommending it, just making you aware of it) that advances both psionic powers and spellcasting, the Cerebremancer which you could enter by 7th level easily and maybe earlier if you use cheese.

Non-psionic characters can also use a wide variety of psionic items to give access to particular powers. Take a look here for more information.

As for a Greater Shrink Item spell, what is it you want to shrink? When you get access to the spell (the regular version that is) you can already shrink down an item of 14 cubic feet... At 20th level, that's a 40 cubic foot item.

EDIT: And if you are using the magic / psionics transparency rules, I think that Wish / Limited Wish / Miracle would allow you to duplicate psionic powers as well, but that would be open to interpretation.

[Psyren]

There's a wizard spell that lets you turn off your magic for awhile to become a pseudo-psion - Mental Pinnacle

For converting spells into powers, Erudites do that, but they are psions to begin with rather than wizards.

You can also look into Binding - Be a Caster/Binder/Anima Mage, and bind the psionic vestiges - you now have spells and psionics (and binding, of course.)

[The Winter King]

40 cu ft is tiny any thing that is 40 cu ft or less really isnt worth shrinking. I ask because my player wants to shrink the corpse of the dragon BBEG Im using and take it home and Taxidermy it, his charater is a taxidermist turned adventurer. I can Homebrew my own if I need to but I would rather use an existing spell to reduce the amount or to base a hombrew on.

[Psyren]

40 cu ft is tiny any thing that is 40 cu ft or less really isnt worth shrinking. I ask because my player wants to shrink the corpse of the dragon BBEG Im using and take it home and Taxidermy it, his charater is a taxidermist turned adventurer. I can Homebrew my own if I need to but I would rather use an existing spell to reduce the amount or to base a hombrew on.

How about Polymorph Any Object? Turn into a rock, put it in his backpack, take it home and then dispel it.