Or you could drill a hole in the side of your HLT and mount an element from a $10 electric kettle (eg. Belle brand from Big W).
They seal well and have a plastic backing nut. I have two in my HLT and they work great, many others are using them too.
However, the above hand held element is a great addition to any brewery as it allows you to heat any vessels with it with minimal fuss. You could potentially heat your HLT, MT and boil your kettle with the one element above.
Hope it's a start. I don't think you got much of a response because there is a search button up in the top right hand corner there and this topic has been covered many, many times-with photos.
Cheers, Justin