i understand you Oz guys have an aftermarket filter avail that works very well. I want to say its Big Kel over on HBF that has one of JRs housings, and knows of the filter, but i May be mistaken.
like a foam filter, grease the mating surface of the filter and the housing. the housing has a throat built in that the filter fits over. grease the outter face of the filter, but leave the area that goes into the throat on the housing dry.
More so you don't stuff the throat with grease putting on the filter. the grease will seal the filter to the back of the housing and ensure all air flows thru the filter. Some of the cheap ass filvers will leak around the filter medium and their molded on ends, as well as be a bit smaller as i noted above, so just be sure the filter is a quality filter, keep it dry and greased, and youll be dandy.