Looking for a Linux based FSK RTTY app -- and Winkey too!

Hello Linux HAMs,

I've been happily using FLdigi for my various HF digital modes but I'd like to try proper FSK-based RTTY with my Yaesu FT-950. Unfortunately, Fldigi doesn't natively support FSK modes nor the WinKeyer2 system:

http://www.w1hkj.com/FldigiHelp/PseudoFSK.html

I'm using a US Interface Navigator unit here

    http://usinterface.com/naviusa_004.htm

which supports true FSK via a basic input via it's fourth serial port (/dev/ttyUSB3). I'm curious if anyone can make some recommendations on either a way to modify FLdigi to support this interface or some alternative program to use this interface?

On a similar note, is anyone aware of any Linux program that support the Winkeyer2 system? It's supported on Windows apps like DM780 and MixW so I hope similar things can be said for Linux. This supported via the third serial port (/dev/ttyUSB2)

Ideas?

--David