Sorry - not able to help. Just got Sky working so tried to set-up Slingbox as I'm off to the States in a week - can't find anything in the sky router for port forwarding etc. and Slingmedia no help (used to be very good). Get the same login 'features' quoted. If you find anything please let me know - I will do the same.
I think I have the answer!!
Run the slingbox remote access using manual setup to get the ip address and port etc.
In the Sky D-Link router go to Services > add custom service > add
add a name (Slingbox) and port (from the Slingbox - typically 5001)
Next in the Security tab > Fire wall rules
outbound add slingbox
In add the ip address of your slingbox
Save and test
Worked for me.