All right, you are a candidate for a JP1.3 cable! Seriously, with several remotes it is really worth the $35 (shipped) to buy a computer interface cable. Then you can upload the IR protocols and devices to control nearly anything, including air conditioners. And, you can take advantage of the 4th device that is hidden in Comcast remotes. If you want to go hog-wild, the red button remotes (and, I think, the Atlas) can accept an "extender" which takes over the firmware in the remote.

No Comcast remote has 1658 built-in, but with an interface cable you can easily upgrade the remotes to have that setup code, or (more likely) a custom setup code that does exactly what you want. We have 3 Comcast DVRs, each with different TVs, etc. and it is easy to set each up so that from a user point of view the remotes all do the same thing.

The steps are to
1) Buy a cable: www.hifi-remote.com/forums/viewtopic.php
2) Download RemoteMaster: www.hifi-remote.com/forums/viewtopic.php
3) Download IR.exe: www.hifi-remote.com/forums/viewtopic.php

Use RemoteMaster to make "upgrades", using the appropriate IR protocol, device numbers and function codes, and then assign these graphically to the remote buttons.  Most likely, somebody has already done the work, and you can just use the file they have contributed.

Use IR.exe to upload and download data from the remote.