Maybe but the 998 does not have some of the sensors that the 1098 has so the canbus would possibly not work? Also I bet many of the plug connectors are different so a lot of splicing would need to be done.
If you have no 998 harness the next best thing is a 620/800 harness almost a straight fit apart from the coil plugs.
I have a mint 620 harness for sale.
http://www.ebay.co.uk/itm/2814265290...84.m1555.l2649