Back again. Just got another Sega Channel Adapter (a Scientific Atlanta, Inc. version from 1995/06) with the standard fare in its original box -- Receiver Cartridge, In-Line Filter (that big block that must be fitted onto the Receiver Cartridge's Cable Input Terminal lest you want to violate an FCC Rule), AC Adaptor, Instruction Manual, and Registration Card. However, there's no Coupler or RF Coaxial Cables (which, based on what I've found after RTFM'ing, you're supposed to route the incoming cable transmission through the coupler and to both your Sega Channel Receiver Cartridge and your TV/VCR/Scientific Atlanta Digital Music Terminal; that way, you'd be able to easily switch from watching cable TV and playing Sega Channel).
After RTFM'ing some more, I found out how one would access the Password for Parents Screen (just in case anyone out there lost their manual): Press the Menu Button on the Receiver Cartridge while holding the A and Start Buttons on the Control Pad.
Eventually, I may put up select scans from my manual if the Terms of Service allows such activity; if they do, better safe than sorry -- 200dpi from my end instead of the 600dpi I work with when I'm translating Japanese manuals.
--Victor Golf Charles