I installed this driver for a pctel HAMR modem in my desknote but later changed to a smartlink HAMR modem driver from smartlink (in the unsupported download section of the smartlink web site) The PCTel 9.6 driver worked but I was one of those who ended up with a sound driver conflict.
When I installed in Slackware the way I always got around the modversions problem was to make sure I have kernel sources installed and then compiled a new kernel.
It is alot to go through but I end up having to do it anyway to get the alsa sound drivers to work. I have an outdated website that describes installing the pctel driver which has been reported to work with the pctel 789 chipset. I now have the desknote running slackware 9.0 with the Smartlink HAMR modem driver and alsa 9.6 sound.. It works so well I plan to leave it alone.
You also might get some milage doing a search on the Conexant HSF HCF modems and seeing if someone can email you the old driver. I rechecked the download agreement and they can be shared but not altered. The drivers fit on a 1.44 floppy and even with dialup can be emailed in 2-3 minutes. I have a friend that has the drivers on his hd and if you know specifically HSF vs HCF (look at you lspci output and post the vendor and model ID numbers I can email you the older 56K tarball drivers. (These will also need kernel sources installed and modversion.h)
Failing that the PCTel driver should work. I would delete your dummy files and follow the kernel compiling instructions in this forum. Keep you first attempt simple and just optimize the cpu. If you plan on the alsa drivers you need to have general sound card support and I think OSS support but no specific drivers.
PCTel 9.6 installation