wvdial is included in the fedora core default installed packages, first check with:
if is installed you will get:
if not wvdial with it is all dependencies are included in the fedora core 5 cd's, you can copy the wvdial wiht it's all depnedencies to the hard disk then install with rpm:
rpm -ivh wvdial.rpm depend..rpm depned.rpm depend.rpm
or other way is to make a local repo from fedora core cd's then run the yum to install the wvdial with it's dependencies, you don't need to be online, or copy all the cd's to your hard disk and use the smart package manager to install the wvdial offline, visit this link
for the help of above procedures.