You have "JUST" to develop normal USB device driver. I have to prepare project based on pic16c7x5 for my master thesis project testboard and I am interested in this topic too. I have found there is a possibility to make HID device that wont need specialized driver and have access to USB device from user space. In the same way works microstar hardware PC key, that I obtained for testing. I haven`t tried to make this technogy to work, but only from reading specification/articles I believe it will works.
You can find firmware examples with this link.
There is also a simple windows driver available.
h*tp://www.microchip.com/1000/suppdoc/appnote/firmware/index.htm
I was playing with this a couple of years ago, got some sample code somewhere written in borland builder.
Downloaded the driver from microchip, damded if I can find it again on their site?
check this link, not for your specified cpu (for the 16f87X) but there are a lot of info about doing the USB protocol stuff that might be of some help.
**broken link removed**
another great recource for USB dev. is www.usb.org, check the developer forum...
Can't find the HIDComm ActiveX Control from the microchip site anymore
but you can find a copy here including firmware examples.
h*tp://www.inex.co.th/dev.html
There is a lot of HID example code here.
h*tp://www.lvr.com/hidpage.htm
**broken link removed**
for an example of HID without the ActiveX Control.