I bought those from Graybar Telecom in Dallas. I don't recall how much they were but they weren't expensive. If you don't find any let me know. I have have seen at least one upstairs and there should be at least one more up there as well.
As for the DTMF decoder, you can make an interface out of a non-polorized capicator and a 1:1 audio transformer across the audio pair that will monitor the line and feed the DTMF into your DTMF activated switch. Pretty basic to interface once you have the access device.
Shhhh. Don't wake Bill from his nap
