I recall a thread about 3 months ago regarding bike access to the Geelong Road, but I couldn't find it in a quick search.
I rode from Torquay to Melb last week and found a very wide and clean bike/emerg lane from Geelong to Werribee. But you do have to get off at the South exit to Werribee, because the double car on ramp on the North side in a bit dangerous.