I got it going today using Signalink usb.
I still want to use it with the PK900 and the PK232usb but I believe I may have cable issues.
My Signalink usb settings are: On the opening screen of HRD go to the upper left corner and click the EDIT tab and then click on CONNECT. On that menu, if you have a Yaesu ftdx5000 it should read Comport 1 Speed 4800 and the RTS box checked.
Then open dm780 Program and click on OPTIONS and click on PTT and choose (in the upper right hand corner) where it says RADIO OPERATION CENTER and put a checkmark in the LET ROC KEY RADIO.
My only connections are the 5 pin cable to the PACKET terminal on rear of the 500 and that cable than goes to rear of the Signalink usb in the RJ45 connector. I then went to the Signalink website and dug up the jumper settings for the Yaesu 5000 and set the jumpers to those settings. DO NOT USE THE SETTINGS ON THE FLYER THAT CAME WITH THE UNIT AS I DId
The other end of the USB connection on the rear of the signalink usb device gets plugged into a usb connection on your computer.
My radio menu settings whether right or wrong are 69 data: 70 = 70: 71 vfo a: 72 = 70; 73 150ms; 74 = 70; 83 = 100; 84 = 18db; 85 = 3900; 86 = 18db; 87 =0hz; 88 = 1000 NOW, THESE ARE NOT LIKELY THE BEST SETTINGS. But they are working on my ftdx5000 at the moment. They will likely change once I get up to speed on what 'm doing.
My first contact (although it was a bit sloppy as been away from rtty 15 years) or so was JY4CI I'm looking forward to February 8th the CQ RTTY Prefix contest.