Ahh, there's actually an install.sh script for installations that actually pulls in all the dependencies and such:
http://webmin.com/vinstall.htmlDon't run that on a working system, that's just for future reference ;-)
In the meantime -- yes, you could recompile suexec, though if you just installed the Apache packages from the Virtualmin repository, that'd handle your issue too.
It sounds like you may be using the GPL version, so the packages for that can be found at:
http://software.virtualmin.com/gpl/For the Pro version, just drop the "gpl" from the URL above, and enter your serial and license key numbers when prompted.
-Eric