The easiest route for the M44 is probably an adaptor cap from VPD running to a Setrab or Mocal cooler. I'm not terribly familiar with the M44 engine...but...if it shares the threaded cap with the E46 non-M3's then they should have you covered.

www.victoryproductdesign.com

Good luck,

Mark in St. Louis
ITS BMW 325is