Adding .scc file to mpeg program stream in Compressor

I'm trying to add a .scc closed captioning file to a ProRes sequence I'm converting to mpeg within compressor. I have a self contained ProRes 720x486 Quicktime file. I'm bringing that into compressor and converting to a pretty much standard mpeg 2 file for broadcast. I'm attaching the .scc in the "Additional Information" tab under the "Closed Caption File" option. I select the .scc here and submit in Compressor as normal. An mpeg2 file shows up shortly after. Fotta love Quick Cluster! What a time saver.
However, the resulting mpeg2 file doesn't seem to have any closed caption information embedded in it. I'm looking at it in Quicktime Player Pro v7.7 with the Closed Caption component installed. I also have a standard Closed Caption decoder but this will only read the 608 variety of CC. Am I making a faulty assumption that I can add CC info to the mpeg data stream through compressor? The manual seems to indicate that adding a .scc file this way should result in a 708-compatitable data stream in the resulting mpeg2 file.

I'm looking to deliver a weekly show as an mpeg2 program stream rather than delivering it on tape. The show is shot in HD but edited in SD due to many of the network stations being unable to air the show in HD at the moment. It should be ready to deliver in HD next season so I'm looking for a workflow to embed the CC info. Actually, will 708-type captioning work in a SD file?
Anyone have any insights into this methodology?

Also, where did the Compressor forum go, anyway?

E=MC2+/-2db