If you do it yourself, make sure you go get some new roll pins. Puter did mine for me and he had a press. Mark the housing and gear before popping it off as it is tricky to get it all lined back up and you definitely dont want to have to press it off and on multiple times. If you don't want to fool with it, do as these guys say. Take it to a machine shop and let them do it. The charge would be minimal I am sure.
2009 Mazda Speed 3
2006 Mazda Speed 6 (wife's car)