Does anybody have any advice on how to superset legs? ie:

Squat: 10, 8, 6, 4 (reps)
w/
Leg Extensions: 10, 8, 6, 4 (reps)

I heard it's best to superset legs in the same muscle group.

no.
http://www.sherdog.net/forums/f13/read-886282/

no leg extensions either

Good stuff, but I found no real info on supersets with legs. That guy knows what he's talking about, but supersetting legs will add some really good definition and muscle mass to your legs, not necessarily strength.

Reading that, it actually sounds very bitter.