I hung my light myself by standing on top of my GC. I put the vinyl cover on (first and last time, ha ha), and layed some folded bath towels on top where I rested the heavy light on the table. I think the biggest danger, is dropping a tool on the table, and cutting the cloth.
Since then, I've stood on the table dozens of times, to take an overhead picture of a layout. When I do that, I wear socks only, and jump right up on the cloth. Never had any issues.
<=== Not a table mechanic, or electrician, but worked great for me
*Edit:
1. I avoid the slate seams when I stand on the table. If you have a 1 piece slate Diamond, then no need to worry about that.
2. My light was not as big a the Diamond light, but it was still a heavy wood fluorescent style light made by Brunswick (not their GC light). I was able to hang it solo, by resting one end on the table (on top of the folded bath towels), lifting the other end, and hooking the 2 chains to the ceiling hooks. Then lifting the end on the table and hooking its 2 chains to the hooks.