yeah, perhaps get your own guitar (doesn't matter how crappy) and compose the guitar parts as well. Write down some tabs and give them to your guitarist,and there you go. He might appreciate the easiness of not writing his own stuff. Now the drummer, I'm not sure about. maybe just mimic what you want it to sound like with your mouth (beatbox, if you will) and try to get him to copy that.
I actually play guitar, I just joined this forum for the band management section