Well, the IR signals are well known.  See for example this thread and the link to Pronto Hex.  That thread also tells how to manually program e.g. a Comcast cable remote (or any higher end remote made by UEI, like OneForAll) to send the necessary commands.  If you get a remote made in the last 10 years or so, it will need 5 digit EFCs.  Prepend 2 zeros to the EFCs listed the thread.

Do make sure to use setup code Video 0582  (20582 on remotes like the Comcast).