If you know can you send me a link to a timetable or something?
You would probably have to take a motorised Omnibus. As far as I know V/Line doesn't have trains running between Geelong, and Ballaarat any more. There was a train service between the two cities once, but the Kennett Government stopped it as part of their procedure to cease all country trains running in Victoria. Only a change of government "saved" the remaining country trains. The information that the Kennett government was preparing to axe all country trains came to me from an ex-V/Line employee.
did you try the metlink website? you just put in your home and your destination and it organises a little route for you. it would take forever though, i think in your case you might have to go to the cbd then catch a v-line down sydenham way..