Originally Posted by
Need
You could do "In Town Check In" at the Cathay Pacific counter in the Airport Express station in HK that morning. Then you just walk over to the HK->Macau ferry terminal and take the early morning turbojet to Macau. In the evening you could just take the Macau to HKG airport turbojet.
You will need to use an Octopus card to open the gate at the Airport Express station to get to the Cathay Pacific counter for check in. You might get charged on an one-way airport express ticket to airport on your octopus card but I am not sure. I did see people just following someone else who opened the gate to get in, but there is a guard there keeping watch.
Yes you are charged the Airport Express trip at the time of check in.
When you then take the direct ferry from Macau to HKG you can collect the departure tax back at the Sky Pier.