Convert USB slave to Bluetooth?

I’m looking for a way to convert a USB slave device into Bluetooth. More specifically I have a telescope controller that can be accessed from a PC by a USB-B port (FT232 based). I’d like to get rid of the cable and access it by Bluetooth (through a virtual COM port). Power is not an issue of course at the controller has it’s one power supply.

Does anyone have an idea how to make such a device? I found some old USB to Bluetooth converters for printers on the web (IOGEAR, Belkin, Primetek), but couldn’t figure out what’s inside of them.

Thanks in advance.