Add a folder in $LOAD_PATH and require all libraries automatically?

Question

How do I tell Ruby to add a path in $LOAD_PATH and require all libraries automatically every time the interpreter fires up?

That is to say, I don't want to load my libraries manually.

Eg:

cd /my_libraries
git clone <git_repo_to_thor_gem>

Then I want ruby to use that one instead of the gem I installed because I want to change the source code and push the changes to GitHub.

How do I do this?

BTW: This is the way to edit source code and push it up right?