Trapping A Mind

For a powerful Mentem magus...

Would it be possible, I wonder, to use Muto Mentem(Animal) (base 25) to seperate someone's mind from their body as a small creature, then Rego Mentem 5 (control a disembodied spirit) or Rego Animal base 2 (as per Circle of Beast Warding) to trap the spirit in a magic circle?

The circle might also need a 'Maintain the Demanding Spell' effect to keep the Muto Mentem in effect, perhaps.

Anyway... once you have this, if it's possible... what can you do with it?

Mind of the Beast on page 149 , allows you to turn the mind of a target into that of an animal.
Increasing by 02 magnitudes to make the mind solid in the form of an animal should work.

Serf's parma, but isn't there already a spell in the core book that changes a mind into a bird or something? Seems like a second spell or the addition of a (ReAn) requisite to trap the little critter.

That would be Inmost Companion also on page 149.

Right. I was referring to the Inmost Companion spell...
That part wasn't really in question at all. It's the other stuff that I'm curious about.