With an electric dremel and a cutting bit.....about 30 minutes to 2 hours depending on beers consumed and how long it takes to clean up afterwords. If you do, make sure you clean the shavings out really good...ie hose it out and finger sweeps cause you dont want plastic fileings to get into the MAF screen.
it'* very easy to gut a stock airbox. take it out. hack it up with a dremel so more air can flow in. reinstall. it'* easy enough to just go buy a cone filter and take a trip to home depot and make your own FWI.