Sony Music Center uses Gracenote. One can look at network traffic via WireShark to see what info is sent to Gracenote servers (API key, etc?)
SonicStage, for CDDB, has a "proxy" option. One can write a simple proxy server that simply interrogates the request to Gracenote from SonicStage, and modifies the (presumably) HTTPS call to use the new API key. I'm guessing a couple-weekends sort of project. Best part is that there is no need to modify any DLLs.
I'm having the same issue -- how to I get a CD onto a MD, with Tags. I tried Sony Music Center /w Gracenote - wonderful. Spot on, album cover comes through. It can even recognize individual songs. I can import a CD to FLAC, MP3, AAC, or WAV. I tried WAV. Music Center did tag the WAVs, but Sonic Stage failed to read the tags. I tried AAC 320 - Sonic Stage recognized the tags, but then I'm using lossy format in the middle of the flow. Perhaps it does not matter since the final destination is LP2 ATRAC3 132kbits format.
Next, as per Philippe C, I will try Music Center to FLAC (with tags), then FLAC to WMA Lossless (w tags preserved), then to Sonic Stage and onto MD.
I'll also try to see if new Sound Forge 13 can preserve tags when doing say FLAC to ATRAC conversion .... (this way I can skip the WMA step).