You won't be able to accomplish what you are trying to do if you are outside your home network. The closest you might get to solving the issue is if a relative or friend could install the free logmein software on their laptop ( www.logmein.com) and then log in to your home network (hopefully they're capable of doing that). Once they've done that, you would, from wherever you are, run your internet browser, install the logmein plugin allowing you to remotely control their computer and from that point, you can access your router settings and slingbox on your home network in order to check the port forwarding settings or re-run the sling setup to manually configure the router for correct remote viewing.
Press alt.shift.i while watching a stream on the desktop software or ctrl and click the screen if using the webplayer to see what stream type comes up. If it's not TCP, then its a port forwarding issue, and more than likely the reason for the slingcatcher connection problem.