Self Signing an MS word macro

I'm just wondering if anyone here knows how to sign an MS word macro? I know there is a tool called selfcert and makecert that comes with office. But I don't have a clue how to use them. You run selfcert and it says a certificate is made, but there is no way to apply it to a macro or do anything with it at all.

All I need to do is make it so macros I create can run with the macro security is set to high. It only has to work on a single computer, according to MS's documentation this isn't a problem, as the selfcert makes a certificate that only that computer would accepted, but for the life of me I can't figure out how to do it or find documentation that actually details how.