How to get trained at other locations as a Seater

I’m currently a resort TSR seater and am looking to pick up shifts outside my home location! I know that some shifts can be picked up untrained, but there are a few places I’d like to try that require training. I’ve tried asking my leaders about it but they haven’t really given me any answers, so I was wondering if anyone here knew how it works. Is it something I can sign up for myself or do I need my leaders’ approval? Any insight is appreciated :)