I got my ADSL PCI modem from Free-online, and their guide worked fine. Have you tried following their setup routine?
I also found that a brief 'phone call to the help line solved every problem I had, even when it was me being an idiot! (although the help desk operator very politely didn't say so)
I believe you'll find that Conexant doesn't make modems (they only provide the chip set) so if you can find the name of the modem manufacturer you should be able to download all the necessary drivers from them.
Finally, as I understand the instructions I got, the PPPoE setup is designed the american 'phone system, perhaps someone else will put me right on that.