You need a good air compressor... running 100% of time... a leak down
adapter so you keep pressure in the cylinder you are working on... to keep
the valve closed...
On your head, I believe you need a valve spring compressor to do compress
it... a magnet to remove the split retainer...
Oil the stem seal before installing it. A long needle nose with a loop to
tap the seal down or similar device to pull and push the seal down without
destroying the seal.
I done it on my 380SE... take a while but not too hard at all with proper