That would be Evan.

Then there is Whitebred that also did it.
http://bansheehq.com/forums/index.php?/topic/164855-first-full-rebuild-since-new/


But before them, Kevin Gigot made EFI for a banshee . This one was in dirt wheels.
http://www.atvdragracers.com/forum/two-stroke-technical/1536-banshee-fuel-injection.html

Here is a trx250r conversion


Here is a company that sell a EFI kit for single cylinder smaller 2-strokes. It has a 28mm TB which is way too much, but they offer a 34mm which might work on stockish 250r.

If you really want to put EFI on a lt250r or zilla, I would suggest buying the EFI system off a LT450R (as it has a 42mm TB ) and buying this ECU (http://pe-ltd.com/assets/pe3-sp000_datasheet_10-5-13.pdf). You then will need to an adapter and PE use to sell them for Lt450r. Next you will need a trigger wheel, easy to mod your flywheel for one. Then you just need to make sure you get everything mounts and hooked up then tuning is not that hard.
http://www.ecotrons.com/products/2_stroke_small_engine_fuel_injection_kit/