the only thing that does not work without magic, is that an external depends on external symbols but does not explicitely define where to look for them (via linking against those dynamically!) and those symbols are not defined by pd (or a library that has been loaded _beforehand_). it will definitely not start to search random libraries (like pd-stable) installed on your harddisk.
well, i'm curious, if this is a linux only problem ... could you try to split the pd binary to a starter application and a shared library (scons pdlib=1)
btw, could you send me the complete output of pd -verbose?
thanks ... tim