Very possible but I think your first order of business should be to get them off of the mouse hoppers and onto Rat pups. Than try and make the switch to FT. Mouse Hoppers are way too small. I know it's not your fault - you just got them, but that should be at the top of your to-do list..
I have switched all of my live eaters (except one) from LIVE ASF to FT Norwway.. It's very possible.
Goodluck!
Chris.