I just went through this myself. I grabbed a monitor from a friend of mine the other day for my Pole Position, turns out it was a med res and neither of us new it. I figured it out pretty quickly after I couldn't get it to sync.
I did some research and found out the chassis could be modified to work with the frequency of med res, but it isn't worth the hassle.
I assume you are talking about using it with an actual game board ? If so, then there's no easy or practical way to use the monitor as standard res or provide any way to switch between the two.
If you were thinking of using it in a MAME machine, I can't help you there, but a search of this board should tell you if it's been discussed, I'm sure it's been done/tried.

D