Any suggestions on Micing a harmonica for a solo?
Depends on the mics you already have. Start with the cheapest stage mic you have and go up from there. Most harmonica players usually have their own mic. I like to run a cheesy mic (with limited response) thru a really small guitar amp, and then mic the amp. There ain't a whole lotta range to a harmonica so unless you really want a hi-fi solo, go for the grit.
Every blues/rock harp player I know uses an Astatic mic. They are cheese in the extreme and add tremendous overtones to the harp. I usually record using a large diaphragm condenser (like my Rode NT1) about a foot away from the speaker of a Pignose or other smaller amp and get a great "in your face" harp sound. A 57 or 58 will work but not like an Astatic.