in the file /etc/sudoers
change the %wheel
entry:
%wheel ALL=ALL,!/usr/bin/rvm
using the correct absolute path for rvm. This will allow members of the wheel group to use sudo
with any command except rvm
attempting to do so will give you a message:
Sorry, user *username* is not allowed to execute '/usr/bin/rvm' as root on *hostname*.
Edit: on my system, the sudo group is "wheel", but you could specify any group to have specific sudo privileges.