I have an older schwinn mountain bike.. it has the standard nut type
hub on the rear wheel..

I've recently acquired a trainer, and for the trainer (Minoura rim
drive powermatic system), they use skewers and recommend replacing the
existing skewer to theirs that came with it, which i did with my newer
bike...

Is it possible to convert the older bike's nut type setup to a quick
release skewer setup? Or cost wise.. would it be cheaper to just find
a bike that could be used as a trainer that had the quick release
(used)...

The local bike store said it wouldnt be possible to convert it.

The bike was originally a 10 speed.. with the front sprocket having 2
rings.. i upgraded that awhile back to 3 ring.. i think its 15 speed,
but the back is the part that matters here i think...

Any thoughts?

Thanks