Recording question

I think you can use the "slave out" on that amp through a cabinet emulator (like the Behringer GI100 Ultra-G DI Box).
 
You definately don't want to record your guitars direct using that mesa. that pretty much would be a waste of a good amp. if you wanted to get decent tone direct, i'd get a line 6 pod or something like that. you should just buy an sm57 and put it in front of the cab...can't go wrong.

however, you can use a direct box, but I don't know what kind of outputs that amp has....you could use silverhaze's idea and just take it out of of teh amp, inot the direct box and to your four track....there is also a technique called reamping which means putting a direct box in your signal before you get to the amp..so it would go guitar, direct box out of parallel on teh DI to the amp, and out of the main output to your recorder...this will take your unamped untreated guitar tone and put it right to tape...i use it when the guitarist i'm recording decides halfway thru the mix that he doesnt like his guitar tone. you make your recorder play the track from teh DI back to the amp...you get the original performance, new tone. just mic up the amp. anyway...i guess if you have a four track you're not gonna be doing that. end of rant.