I usually give them a call about a property they have listed as a short sale, though a face to face over coffee might be more effective. I make them fully aware that I'm an investor and what my intentions are. Of course I also let them know they can collect twice on the commission as well. Some of them won't listen at all, some want to hear more and some are more than happy to hear from you. Keep in mind most of them will fall off the face of the earth, never to be heard from again. I think a lot of that is because of negative press on short sale investors.
I just got a Broker onboard yesterday with 2 deals. He had done his homework and asked around about realtors experiences with letting an investor handle negotiations. He did say that several said no way, but 3 did tell him that was the only way they would work them. Less work for more pay.
I have had the same realtor vanish on me twice. She had came back, more than happy to work with me, then "poof", she was gone again.
The realtor I'm using to list my direct to seller listings should end up being a big resource for leads. I offered him the opportunity to list a property for me without asking for any leads. He has 16 short sale listings and has hinted around about having me put in some offers. You might want to try this approach. You're kinda proving yourself without asking much of them.
Hope this helps.
Kyle