This particular driver is from the XL766 restore disk, MODEMS folder. It's doesn't have a fancy install program so you will have to use the ADD NEW HARDWARE icon or just click the MODEMS icon and select "Have Disk". Then point to the appropriate folder where you unzipped this file to.
Unzip to a temp folder. You will now have 3 sub-folders:
I believe these drivers include several Pavilion models... not just the XL766. So you may need to try all or several of these drivers to find one that works. HP doesn't offer these restore disks any longer so perhaps you can benefit fr