I have to wear a conservative suit for work 4 days out of 5, and sometimes for after-work cocktail parties. I think anything mentioned by Jock and Zardoz is good, and you have Zardoz as a good model, too. As you say, a solid white shirt (but, no button-down collar for this event if you can avoid it) and well-polished shoes. Also, any long tie appropriate for business would do (IOW, avoid a Mickey Mouse tie), and don't let the tie go beyond the top of the kilt. Some say a tie in another tartan of the same clan as the kilt is okay, but I personally don't like to wear tartan ties with the kilt. A tweed jacket is fine, but a black, barathea kilt-cut jacket is an option, too. You can probably get one off-the-rack and sized pretty quick. Like Jock Scot says, go with solid hose and avoid the white, if you can. Compared to all the dark suit trousers, white hose will comparitively appear to glow in the dark.