For changing the seals. i used a compressor and a tool i have that goes into the end of the compressor hose, then in the the spark plug holes what puts pressure on to the valves, so they dont fall into the chambers. Easyier then taking the head off.
tools i needed.

compressor
Compressor valve
Valve stem tensioner thing to push the springs down.
Im sure some of the lads on here will tell you an easyier way...