yes, re-running the setup has to be done at the slingbox location, but if you can create a free account from logmein, then from there provide him with a link to install the software from logmein onto his computer, you could take over his computer temporarily at your slingbox location allowing you to run the sling setup from where ever you are to make the slingbox functional again.
I connect remotely to my home network using this setup if I need to change any settings on my slingbox. It's worth at least trying if you run out of options.
.......or if he's tech savvy enough and he probably is if he can set a static IP address, just get him to go through the setup process on his end once you've provided him with your sling account info and talk him through the setup. Any computer can run the sling setup as long as it's on the home network.