thanks for asking.

I'd love to create a Behaviour for the SlingPlayer myself, but don't 
have a SlingBox. There have, however been a number of people who 
wrote me they had created a Behaviour of their own and that it would 
work great. So I guess it's possible.

After all, all you have to do is:

1) Find out, which keys you need to press to achieve the things you 
want to achieve in SlingPlayer. 
2) Follow the Behaviour Construction Kit video to learn how to 
quickly create a Behaviour (< 5 min). 
3) Create it (< 5 min). 
4) Choose "Compile & Testdrive" to test the Behaviour - or "Export" 
to export it to RB's default location for Behaviours, so it is 
available on the next startup.

It's really, really simple.

Finally, I'd love to hear from you if you got it working, so I have a 
chance of adding SlingPlayer support to RB right out of the box. All 
I need is an action pack of the actions (which is as simple as 
selecting all of the actions you created, then choosing "export 
actionpack" in the lower, right corner of the BCK's Action Factory 
pane) to the info address at iospirit com.

Best regards, 
Felix