TempDB not selectable for DBCC maintenance plan
Tempdb won't be available for you in the Mantainance Plan database list box, but you sure can run it as a script:

DBCC CHECKDB(N'tempdb')  WITH NO_INFOMSGS


According to Mr. Brent Ozar, you SHOULD check tempdb for integrity, and if Brent is saying that, that is good enough for me.

regards