Modularising Tests

I want to be able to share some of my test scripts across many use cases so that I dont have to keep creating a script for things like logging in to the application under test.

I am finding this difficult because of the way I am structuring the tests. I am currently using a separate project in TC for each use case and have found that each project cannot 'see' the tests or units in another project.

I could either restructure the tests so that all use cases are in the same project or copy the repeatable tests across to the other projects but neither of those are very elegant.

Is there another method available in TC that would let me share tests across projects?