You can, but with a little patience, they will come to you anyway. I wondered that stuff myself when I first became a mentor, but then I saw someone else post something like "I want students who WANT to be in the Mentor Program, not students I have to CONVINCE to join" - and that was kind of a light bulb moment for me.

One thing you could do (if you really want to find some students) is look for new members, and then leave them a welcome message on their wall, offering help, etc. if they're interested. That would be nice and very personal, I think. In the long run, you WILL get students even if you do nothing.