Re: Borrow a rear sight adjuster tool for a 1911?
As above stated...punch, hammer, vice with plastic/rubber jaw covers or tape the slide.
Put some masking tape on the side of the sight before you use the punch and it will help from marring it up. Also, make sure the punch is the proper diameter...if it's too big or too thin, less energy will be delivered into the sight.
The sight tools are nice if you happen to have one handy but they are far from required.
for what it's worth, I've used steel punches more times than I can remember on customers guns...never an issue with marring the sight. Actually I've had more issues with brass leaving a mark (hence the tape).