Welcome to MarTT's fotki!
Use a turkey baster to remove as much coolant as you can prior to removal. Then add it back when you've installed the new tank.
- remove engine bay cover - 1 phillips
- remove coolant level sensor
- remove 2 phillips screws holding tank down
- release and push back hose clamps (2)
- remove hoses, top then bottom.
Install is reverse of removal.