You probably don't need to.

Since we're using a distributed version control system, though, you can have your own repository. In fact, if you've cloned the source, you already have your own. You can either upload that to some webspace you happen to own, or you can use one of the various free mercurial hosting services, like bitbucket. When you've published your repository in one of those ways, you can show your brilliant piece of code to one of the people with write access to our repository (go to the IRC channel and look for the people with an @), and ask them to push the changesets there. They'll have a look at it and determine if your changes are fit for incorporating them into the source tree.

If you don't have a public repository, and don't want one, you can use the patch export function of Mercurial and attach the patch to a post here in this forum, or attach it to a bug in the bugtracker, and direct the attention of one of the developers there. Once it's approved, it will look exactly like you have pushed the changeset yourself, no Signed-Off headers or other mumbo jumbo. Nobody will ever know the difference!

If you still think you really need an account, you're welcome to ask Isilkor or Günther. You should have some compelling arguments why you can't just use bitbucket though.