Hi Den, feel free to use my interface as you wish, absolutely no problem! It was initially intended for use with YPlog, however the keying circuit can be quite easily used for psedoFSK for RTTY with fldigi. I operate now CW only but if I wanted once to return to RTTY I would use an Arduino module for FSK in the style of TinyFSK (I hate AFSK). Anyway, there will be probably need of a modification in the fldigi sources. You can use this as a permission if you want.
73, Martin, OK1RR
 
P.S. If you use the comcast.net don't be surprised if you miss a reply to your email. They using a very stupid method of spam blocking, I highly recommend to use another provider.