I see the libXpm-devel rpm here, but not for CentOS 4.x

http://rpmfind.net/linux/rpm2html/search.php?query=libxpm-devel

And here is one for the i386 platform.  Is that good?

ftp://rpmfind.net/linux/fedora/core/development/i386/os/Fedora/libXpm-devel-3.5.6-1.i386.rpm