Can you emulate an FT232R on the FT90x for example?

The FT90x device can emulate an FTDI D2XX device to the host PC and the data is sent back and forth on the D2XX channel, between a terminal PC application (for example) and the User Firmware application.

The default USB settings like VID, PID, Manufacturer and Serial Number can be changed using the FT900 Programming GUI Utility’s D2XX tab. See AN 365 FT9xx API Programmers Manual and AN 360 FT900 Example Applications for more information.