No machine shop necessary if you are a decent wrench. Tap old ones out, tap new ones in, i like to heat the head to 400 to make it easier. I also cool the guides in a tub of ice. No biggie.
I have never replaced a valve guide by myself, so what I wrote is what I've learned from several places including Honda's service manuals.
What I've learned is required to do a decent guide replacement:
1. The new valve guides need to bee reamed to spec after being driven into the head.
2. A new valve guide might be centered a little bit different than the old one, so the valve seats should be reground - a task that requires tools more expensive than having this work done in a machine shop.
But as I said - I've never tried to do it myself, so my info might be wrong...