Suggestion, post this in the electronic chat where it belongs instead of the off topic forum. You may get more responses.
This is easy enough, build a simple oscillator such as a 555 at 60 hz, then build a simple power supply (transformer, diode bridge, filter cap) after. The difference is use a step up transformer instead of a step down.
To vary the voltge very the amplitude of the 555 output. Easy Peesee.
I doubt you will get 1000V though, maybe a 100. Didn't you get a thread closed once for this?