I think you're getting confused by 2 databases.
1. There is a pkgconfig database usually in /usr/lib/pkgconfig. That has little files for every source installed package, and every rpm that bothers to update pkgconfig. This is consulted by the ./configure scripts
2. RPM keeps a system database of installed rpms and will not install without complaining if your new package requirements are not met in that rpm database. It never thinks of looking in /usr/lib/pkgconfig, because it's stupid. You can tell it to go and play in the traffic (Options like --nodeps --force --ignore-sun-behind-cloud-errors, etc :-), but then it becomes useless to you, because it will complain you don't have the things you actually do have.
wget simply performs a http://somewhere
--> file in most cases. You should have it. If you don't laziest thing might be to boot on some boot cd, mount your disk and do your wget-ing that way.
Search for RH rpms when you want stuff - that's my advice.