? Can you overcome the roll with full opposite rudder? Is there any way to release the stick, if you apply as much force as you can?
a lot of factors come in here, first of all controlling it will depend on how much aileron was in when it jammed - just a little will be fairly controllable, full probably totally uncontrollable. Releasing it will depend on why it has jammed and with what - it may be something like a spanner in the control run , in which case you would need to unjam it, if there was more than one of you in the aircraft then someone might be able to clamber down the back and free it or ot may come free with a little manoeuvring, if it is say a flimsy biro or something else fairly weak then yes you may be able to use brute force, but you might be surprised how much force is needed! one of those problems that depends on exactly what the problem is.
For elevator, yes, you can use trin and power. Both are worth having a practice, as is jammed throttle.