[mrlaser]

While waiting for suggestions, I came up with this solution. I found a washer with an inside diameter which matched the diameter of the valve sleeve. I epoxied the washer to the valve spring compressor to ensure stability. This enables the valve spring to be compressed and the keepers to be put in place. The unit was placed in a vice to allow both hands to be used. It worked perfectly. I'm sure there are other ways to safely install the keepers but this worked for me.