What you want to do is copy the existing copy of standard.jar to livesite_customer_src/lib, so you're sure you have exactly the same version and won't break other dependencies. Then, figure out the version of standard.jar that is bundled with whichever version of teamsite (inspect the META_INF/Manifest.mf file inside the JAR) and go get yourself the version of jstl.jar that corresponds to that.. meaning get the latest version of jstl.jar that does not depend on a standard.jar that is more recent than what iwov provides.