[CentOS] gdb question

If you are trying to debug a core dump from a different machine, how do you tell gdb where to look for the debug info files to match the shared libs that you have in a non-standard location? It finds the shared libs themselves with a 'set solib-absolute-path' directive, but it doesn't look for the corresponding (relative) usr/lib/debug/... file that you get if you extract the debuginfo rpm in the same place. And if I set debug-file-directory to the top of the tree, it wants to also add the solib-absolute-path to that. Is there some way to make it realize that the top of the tree is the same for both?