Sorry, I didn't consider having to buy tools. A good valve spring compressor will make the chore much easier. But if the budget is busted, a tool like shown below can be bought for under $10. I forget exactly where I found this one, it was a parts store though.
Cloths line can be used through the plug hole to wedge the valve closed for removal so a compressor isn't necessary. This has been covered here and elsewhere, I'm sure.
This tool (shown upside down) is used in place of the rocker arm. When the nut is tightened, the ears of the compressor bear down on the retainer. A different, non locking nut (and a washer) is used in place of the standard rocker adjusting nut.