Summary: This paper discusses an approach which aims to provide legacy message passing libraries with Java-like portability in a heterogeneous, metacomputing environment. The results of such portability permit distributed computing components to be `soft-loaded' or `soft-installed' in a dynamic fashion, onto cooperating resources for concurrent, synchronized parallel execution. This capability provides researchers with the ability to tap into a much larger resource pool and to utilize highly tuned codes for achieving performance. Necessarily, the Java programming language is a significant component. The Java Native Interface (JNI) is used to wrap message passing libraries written in other languages, and the bytecode which is generated for the front-end may be analyzed in order to completely determine the needs of the code which it wraps. This characterization allows the pre-configuration of a remote environment so as to be able to support execution. The usefulness of the portability gained by our approach is illustrated through examples showing the soft-installation of a process using an MPI computational substrate and the soft-installation of a process which requires a C-based communication library based upon the efficient multi-cast communication package, CCTL. The examples show that significant gains in performance can be achieved while allowing message passing execution to still exhibit high levels of portability.