You've fallen on your feet I am the only person on this forum who builds Custom Remotes and I also happen to own a Sky Box !!
Interestingly I was not aware that you could change the Remote Address on the Sky box, so that is very useful.
I'm a bit confused by your post as Port 0 on the SPC-4 is for a standard Sky Box, so the built-in remote should work. The other three options are for Port 1,2, & 3 where the address is different.
So here are the Custom Remotes for these 3 ports. Unfortunately they have to have the same filename so I have added the address in brackets after the filename. So to use the one for Port 1 rename the S1123_PL.BIN(1) file to S1123_PL.BIN and use the instructions at http://placeshiftingenthusiasts.com/how-to-install-a-custom-remote-onto-the-slingbox/
Any good ?