Once you have the Tivo on your account, go under DVR Preferences, and check on Transfers and Downloads. It may take up to 24 hrs, but it will have the same MAK as the others on your account.
Series 2 (Retired, sold)
TiVo HD 1TB (157 HD Hrs, PLS, "S3HD")
Roamio, Oh Roamio!
The TiVo Apocalypse begins on Sat 2013 Feb 16 00:00 GMT!