"is it not a part of wvdial?"
My version of wvdial (1.42) supports dial on demand. The version that comes with SuSE 6.1 probably does not have this feature. You can look in /usr/share/doc/packages/wvdial to find out how to set up dod if your version of wvdial supports dod. Otherwise you can download the source for the latest version of wvdial and compile it on your system. It is very unlikely that a SuSE wvdial rpm from a newer release of SuSE will work on SuSE 6.1.
Be prepared. Create a LifeBoat CD.