Both air and manual professional quality guide drivers are available.
A slight angle relief is cut into the driver to prevent mushrooming of the guide when driving it.
I have replaced the MoPar guides and Packard guides using a manual driver..(better control) and heavy weight hammer.
I Line the tappet chamber with a towel after all the springs and valves are out.
This to keep the broken off guide ends from falling into the tappet chamber pockets etc.
Pount them down, break the lower part of the guide off as the guide gets close to the tappet. I use a heavy steel drift. They snap right off.
Drive the new guides in orientated properly...exh/intake and to the exact depth.
You need to hold the driver firmly and accurate, be able to use a heavy 2 lb hammer and swing it straight and solid to hit the guide driver.
That's how they did it all the time back in the old days doing flathead valve job work..right in the car.
I prefer the machine shop to do that job always with the engine out.