Is there a run utility for fvwm (i.e.: like fbrun for fluxbox, or alt-f2 in kde)?
You can use whichever run utility you want. I think most people prefer gmrun (which doesn't depend on gnome afaik). You could also code up one in FvwmScript, assuming it hasn't already been done.
I am a gated community.
There are plenty of configs already made on fvwm's forum. I know I remember seeing many configs that had run scripts in them.
It might be faster to code one up, but, it might be easier just to use something like gmrum.
And on the 8th day, God gave the people Google so that all the problems of the universe could be researched from one central place. And it was good.