look here for a few suggestions, the waistcoat is a good idea, or the bowtie
http://www.alexismalcolmkilts.bigstep.com/generic7.html

http://www.kilts.biz/catalog/tartan_...mmerbunds.html
better still, buy a kilt, and wear it with the tux jacket,modern looking.
braces (suspenders in U.S.A) too maybe a good idea
or even tartan cufflinks
http://www.weetartanshop.com/storeclans.htm