If I ever wanted to that route, is the Kick one of the easier models to mod? The Rebar head on a Kick would be a cool franken mt..
I suppose you could, if you really wanted. The biggest issue would be undoing the knurled screws without smurfing them up. loki-mobile is selling wrenches that will fit these screws, or you could use a two Kick pocket clips as wrenches (wont work on all of Rebars screws, one set is a different size).
If you can get the screws off and on easily on those two multi tools, they are very easy to mod (like legos, almost).
I'd say the easiest leatherman to mod is the new Wave or the Sidekick/Wingman/Rev family. No knurled screws (yeah, they are that big a PITA), just some security torx screws you can undo with hardware store bits.