make a differential probe?!?

[Dave02]

I would like to make one of those HV differential probes that everyone makes, they go to around 500v. Enow got my hopes up with the Oct 92 issue, where there is feature article about these probes and a schematic, or simplified schematic. Unfortunately not enuf details are included. After checking everywhere for differential amps or probes,nothing leads me to a good ready to go schematic that will take the pain and suffering of having to design one. I'm sure with good construction practices that copying an original Tek, T.P.I.,Probemaster or A.P.I. schematic should work o.k. (I didn't say great).
Any help with a schematic would be greatly appreciated and any tips I may need to know. I suspect some one will tell me that it is not as simple as it sounds, and differential amps are a tricky tackle, or perhaps my worries are speaking.
Dave