Are you aware of the patchelf tool? It lets you update the RPATH embedded within the .so files so that they can find other .so files without using LD_LIBRARY_PATH. You could run it on the perl Sybase/CTlib/CTlib.so and then perl would always be able to find the sybase libs. You could even run it on the fly as long as CTLib.so was writable and you modified it prior to loading it :-)

Your re-exec option is probably cleaner since you're using the official way to configure the sybase lib location, and won't get lost if you install a new version of the module, but I just wanted to let you know about another fun option.