Step 1) Sign the (or, if you're representing an organization, use the ), and get it to us. It's a very simple one page document. The Free Software Foundation has a nice page on why they have the same policy we do at http://www.gnu.org/licenses/why-assign.html.
Step 2) Post patches to Ignite, then bug us about them on IM if we forget to review them
Step 3) (optional) If you've demonstrated that you're a reliable and skillful contributor, we'll probably offer you commit privileges for convenience.
(document copied from David Smith document "How to contribute code" in Developers forum)