On the fly compiling of dll

Hi.
Parden me if I do not express my question very well.

A project I am considering would benefit greatly from the ability to to compile a dll at runtime, on machines which may or may not have appropriate tools installed (so I may be looking at using third party tools if available)

For example, User runs my executable, which creates a dll with a function they want to use, selected by them.
My executable adds the function(s) and compiles a dll and outputs a usage txt file.

My questions are: is there some sort of tool/portalbe app I could use to accomplish this? is there a proper name or term for what I am trying to accomplish?

Any tips or comments are very welcome. - Full Post