There are several auctions for the hd connect cable on ebay; use the following for your search:
slingbox pro hd
The HD connect cable does NOT allow your slingbox pro to stream in HD! It only allows for the connection of HD equipment or any equipment for that matter to be connected to the slingbox pro via the component video cable set method.
ONLY the Slingbox Po HD model from slingbox allows for HD streaming both locally and remotely (JUST FYI, remote HD viewing requires an upload bandwidth of at least 3.5 mbps).
I have connected a hd connect cable to my singbox pro and absolutely cannot get it to strem any video or audio...the passthrough works great and the s-video I left connected works great...when I switch my video input to the component I can use the remote and see the optimiser working but no adio or video...any ideas before the HD connect goes back to Ebay??