Unless you get the dev package for those Bluetooth devices (and even then) it will be difficult to convert those serial modules to Joystick Bluetooth devices. I have some of those 8 dollar BT serial devices and am on the email list for the dev environment for them. However, they are a completely different animal. You have to connect a custom programming device to the ones I have to even change the firmware. I have not done this as I am using mine as serial devices.
One thing you could do is use 2 micros and 2 bluetooth serial devices. Have one micro collect the analog data and send over a bluetooth master device, then have a bluetooth slave device grab the serial from it and send to a micro connected to the computer (the one on the computer would be set as a joystick USB device). Even this might require the dev environment for those BT devices. I don't know.
Another possibility is use the bluetooth serial device and write custom software on the PC to emulate a joystick from inputs from the serial device.