Interesting.   Major issues would be model year of engine/trans.  97
and older Mitsu would give you 4 reverse speeds and one forward if you
mount it as a GM configuration and the brake master cylinder would be
in the way if you mounted it the same as the Lancer.   98 and newer
could work.  Here is a list of possible issues:
Mounting points will need rethinking and rewelding.
Engine height clearance may mean the engine/trans sits too low or the
hood gets modified.
Exhaust hook up - custom pipes.
Axle length and spline at either the trans or the wheel spindle or get
the two reworked at a machine shop.  Imagine the replacement costs
down the road.
Wiring hookups and which computer to use, which throttle
body/injection system..
Auto trans is likely a 4sp overdrive and has it's own computer.
Standard trans is a nice 5 speed with hydraulic clutch cylinders.

Keep me posted.  If you get it figured out at a reasonable cost, Ill
do the same.

Pete