I am using DDWRT on an Atheros-based router with the vhusbdmipssf server. I have successfully shared an hp photosmart 7700 to clients on both Windows 7 64bit and OS X 10.9.5. I have also successfully shared a CanoScan 8800F to the client on Windows 7. However, on OS X, when the default Canon scanning application (MP Navigator EX) begins scanning, the vh client "resets" -- i.e., the client appears to lose all connection with the server (the scanning software says that it "cannot communicate with scanner"), the client re-displays the pop-up window with "VirtualHere USB Server Trial Edition, and the connection to the server is reestablished after clicking OK in the pop-up window. If anyone has managed to get a CanoScan working with VH, then please let me know the details.
BTW, I do not see the scanner listed if I try to add it via Settings, Printers & Scanners.