Oh, Federer would definitely double-bagel me. But I think I can still win a few points here or there.
Here's how I would do it:
1. Kamikaze serving and volleying - I would go for my biggest serve on every serve, 1st or 2nd, and if it goes in, I would rush the net and just guess to one side or the other. Sooner or later, I'll guess right a few times and either smack a volley into the open court or hit a drop volley.
2. Go for broke on every return - assuming that he has to hit a 2nd serve now and then, I would just go for a crushing winner into the corner on every return I can get my racquet on. I concede that I would never get my racquet on any of his first serves.
3. Aim for the netcord - if I get into a baseline rally with him, I'd aim for the netcord on every shot hoping that one ball would clip the netcord and dribble over for a free point.
4. Lots of drop shots - if I get the opportunity, I'll go for tons of drop shots. One will likely work sooner or later.
5. Try to shank the ball on purpose off my frame - one may just drop in for a winner and surprise Federer.
6. Hope for double-faults - yes, even Federer will double-fault now and then, especially if he's bored and loses concentration.
7. The "Michael Chang serve" - Yes, after blasting every one of my serves for several games, I'll surprise him with a puny underhand drop shot serve. It just might catch him off-guard and get me a free point.