Check out the following...
http://www.schroth.com/produkte/aviation/index.htm
Click on "Restraints" on the left. I don't know if they have any "approved" kits for the R44, but I'm sure they can tell you. I know that they also make "water activated" unlocking mechanisms for restraints. If you have to ditch and do not manually unlock your harness within three seconds or so, it will unlock your harness for you... pretty cool.