You log such time in the "multi" columns in your logbook, both in Australia and in New Zealand. In this context "multi" refers both to centreline thrust and non-centreline thrust multi-engined aeroplanes.
You log C337 (or any other "centre line thrust multi engine a/c") time in the multi column of your logbook. Don't listen to any idiot telling you otherwise.
My NZCAA logbook says at the bottom of the first page....
Centre-Line Thrust Aeroplanes: Time spent in centre-line thrust aeroplanes shall not count as multi-engined time
Check you local reg's but as far as NZ is concerned it maybe an a/c with more than one engine but cannot me be logged as such
Now for the rotor heads..... with the above quote in mind you presumably cannot log multi time in a BK117 but what about the likes of a chinook???