#1
Are there any sites (or people) that could show me how do this? I'm interested in buying an Epiphone Valve Jr., but I want to use my old combo as a speaker for it. Thanks in advance.
#2
Yeah, I don't think it'd be hard at all. Open up your combo and see what the impedance of the speaker. The Valve Jr. seems to be pretty versatile impedance-wise. Then you'd just have to install a 1/4" jack somewhere on your combo and attach a couple wires.

EDIT: How good it sounds is going to be another story. What was the power rating on your combo?
MG Free At Last
#3
Power rating as in watts? 38. And this will just be a kind of quick-fix until i can afford a decent cab.