Private server KA

Hey, so ive been using MAFIA VIP client for a few different servers, and they mostly have kill aura implemented. I was wondering how you would add this to your own client?

Most servers have projectiles client sided, so by changing the radius for hit detection, you create this hack. For easy searching, the default radius is 0.5 tiles.

So im guessing its possible with example JPEXS? Or do i need something else to be able to change the radius