I would urge you to try freehanding it. It takes a bit of practice, and stopping and starting can lead to some odd results but I find that exactitude about the honing angle is not as important as a consistent angle. So, 24 or 25 degrees - who cares?
The thing is, once you have mastered it. it's like riding a bike. I probably only sharpen chisels every few months (not being doing much woodwork lately) but it's still 2nd nature.
The trick is to not swivel your wrists as you move back and forth, because that will cause a rounding of the honed edge, but to achieve whole arm movement, if you get my drift?
Once mastered it's a darn sight quicker than setting up a guide - or so I found. My guide's in a junk box somewhere.
On a related note. My 78 year old father-in-law was a time served journeyman carpenter and he never used a different grinding and honing angle, nor did he reverse the chisel and remove the scurf - reckoned that it all helped the cutting action