Marty,
I haven't used live sand before, as I have always had an abundance of live rock-which will create live sand.
I have added new sand to an existing system before. I would use a cup or small tupperware to move the sand in. After collecting a cup 3/4 full, slowly lower the cup into the tank with the top facing upwards, once the cup has topped-off with tank water you can then lower your cup to the bottom of the tank. You can now slowly pour or scoop out the sand at the bottom, thus eliminating a larger sand cloud. You will get some sand cloud, but it should be much less rather than dust dumping in sand from the top of the surface!
Goodluck
cheers, Rich