Depending on your distro, you should be able to just download the kppp.rpm and install that way
http://rpmfind.net/linux/RPM/redhat/updates/8.0/i386/kppp-3.0.3-3.2.i386.html
And Suse Linux for example has kinternet which I think is easier and more user friendly than kppp but then again that is just my personal opinion.