Never underestimate the power of a good penetrating oil like PBlaster and time. Apply it at night and let it work while you sleep. Put some on again in the morning, tap it a bit to set up vibration, and let that soak for a couple hours. Then try it. Also, make sure you are using a 6-point socket and a breaker bar. And if none of that works, try putting a length of pipe at the end of the breaker bar to get more torque. If you are using just a regular ratchet or box-end wrench you're in for a world of hurt. I just did this so I know what you mean about that one bolt being a bitch.

Maybe the best thing would be to spring for an impact wrench. If you don't have or want a compressor, get an electrical one. You'll never bust your knuckles again. And you'll curse yourself for not getting one sooner.