Hey Chuck
Dont have any need for BluRay personally, haven't ever used the FCP7's Share to BluRay function, don't have a CompressHD nor do I have a BDR-203 .. think I must be in the wrong thread.
FWIW, I do have a Matrox MXO2 MAX box though (which has the CompressHD hardware embedded in the form of onboard Matrox MAX encoding chips). As noted, I don't do BluRay (have zero need for it meself) but I can tell you broadly how it works in that you use the the normal Share menu (or Send To > Compressor and Export > Using Quicktime Conversion methods) to target your encoding, that being a Matrox MAX / Compress HD H.264 for BluRay preset ... then after the box/card has blazed through the encoding you can use a third party app such as Adobe Encore CS4 or Roxio Toast 10 to author and burn your disc without re-encoding
Plenty of info on their website and in many product reviews across the web
Best
Andy