tips on loading CE5 drivers in CE4.x?

I've got a device (USB Ethernet from Portsmith, PSA1U1E) that has CE5 drivers available in the HCL and from the manufacturer. I'm trying to use this with my Sig3, so CE.NET 4.1. I've hexedited the DLL for the version and exec check seems to be ok with it but it refuses to load. I've also checked that the hardware ID of my device matches one of the PSDUE entries in the registry (it does).

Does anybody recall any tips for loading CE5 drivers in 4.x? Was that a thing that was frequently possible?


Thanks for any help/info/suggestions!

p.s. I contacted portsmith and they got right back to me but stated that they no longer have the source code for the driver sadly :-(