can you practice a solo that is orignally played at a speed much higher than you can do and work your way up to it with a metronome?

or do you have to practice chromatics and scales and build up to that speed before you can do it?
yes, in fact i highy recommend playing something slower and working your way up. but practice it with a metronome.
Definately. I learn a riff or solo just with the text tab at first, memorize it, and then practice it to a metronome later. I'm not talented enough to practice it to a metronome at the very beginning :P