ideal way to load modules / set up evaluation environments at runtime.

Hey guys, I'm trying to load module definitions, and set up evaluation environments outside of the context of the command processor. The apis to do that seem to be lightly documented if at all though. I was wondering if any of you had some insight into the best way to do that. 

For instance, I'd like to :
- load a set of files containing module definitions
- create a new package with a subset of those modules opened, as well as standard modules included with scheme48
- evaluate code in that package

Any help would be appreciated. I need this to replace the module set up directives in scsh, since the api the last version used have changed substantially. It would also be useful in countless other contexts, of course.

-Roderic