Hi Tim, and thanks. Here is the text of the reply I have had from Gene Chimausky (who makes the as909 clone). You may find it interesting and perhaps be able to decipher it.
"There are 2 ways to drive the clone for guiding using the cameras you mention.
The clone provides an ST4 guide interface input, this is a 6pin interface with ground wire and 4 other wires for N/S/E/W. The 6'th wire is unused.
To drive these pins requires something like Shoestring's GPUSB interface which is controlled on the PC side by PHD or K3.
So you would have:
PC->USB->GPUSB->ST4Cable->(909->AuxBusCable)->Scope
Both K3 and PHD support the GPUSB.
The second way to drive the clone is via the clones native USB/serial interface. This is a 3'rd party cable made by FTDI that plugs into the USB on PC and into a jack on the clone. It requires the ASCOM 4.1 platform and uses an ASCOM driver I supply. You can see it in action in the YouTube video I did:
http://www.youtube.com/lynol1000
Advantages of GPUSB: Works on PC and MAC, works with any scope needing an ST4 guiding input, well respected interface device
Advantages of clones native USB interface: Cost
Flashing: Your 497 may or may not need flashing. When the 497 powers up it queries the motor controllers for an ID. If the 497 sees an ID it alows to work with the 909, all is good. If it does not see an ID that is allows then patches would be required. I have see new scopes not need it and 2 year old scopes need it, go figure."
cheers
Peter