Using Twain on HP Laserjet 400 Pro MFP 475dn

AS far as I can tell HP Laserjet 400 Pro MFP 475dn scanner is NOT TWAIN compatible

Using Twack_32 from  twain.org shows the scanner as WIA .... but when checking the Twain 2.0 option in the menue, it's not listed (Opposite goes for twain-compatible Canon Scanner - It's visible when Twain 2.0 is checked, but not when unchecked)

I need TWAIN as the software, running on a Citrix server, looks for a twain scanner. (The citrix forwards the Scanner nicely, but as a WIA scanner. Works from twack32 on the server as well, but not from Paint on the server)

Is there a way to make HP Laserjet 400 Pro MFP 475dn talk twain? Some additional driver? some WIA to Twain conversion?

Any help would be appreciated!

/Jonas Bergstedt, VMI