Here is the procedure to the best of my memory.
I used this driver set with the following:
Motorola V300 cell phone
MV6-DC Hotsync cable
These are the steps as I can remember:
Plug in USB cable
Attach USB cable to phone
Add new hardware
Add USB device
Click "Have Disk" button
Click "Browse" button
Navigate to directory with the drivers
Select Motorola phone
After the first driver is loaded Windows will detect new hardware again.
Do the above steps but this time add Modem instead of USB device.