Ah, the finishing accoutrement I couldn't find! My father found these, with his amazing sluethy skills:http://www.stacyadams.com/shop-sa/mensShoes/classic/madison/prod00015.html
This is the honest to god men's dress boot. pretty much historically accurate. this is the boot they sell at River junction, only this is the site of the people that make them (a zoot suit and pimp clothing outfitter, funnily enough) and so there are more options.http://www.leatherglovesonline.com/pages2/mc1a-d302.htm
This, as far as we can tell, is the only real white kidskin glove anywhere on the market. The only frigging one. and these are the only guys who sell it. it's mostly the correct shape and style, too. kidskin (that is to say young goat skin or cabretta) is the only correct material to make a true gentleman's formal gloves out of. The gloves were nearly the only part of a formal getup that allowed for customization: it was intermittently popular to wear your gloves in any variety of white, off white, or light pastel hues... since you can buy them in white here, you could presumably gently dye them yourself.
The cane is the easy part. almost any antique store has a rack full of old canes, and most of the ones you find would likely be appropriate. I'm thinking of looking into a modern material beat-the-shit-outta-someone cane, just for kicks. maybe even a sword cane. but really, I should just make myself one of those.
The only thing I think I need to locate now is outerwear; I've seen a few period greatcoats, which mostly only work with military outfits, not formalwear. The appropriate thing to wear over a frock coat is the aptly named Overfrock, which is the exact same thing as a frock coat, only cut a little longer and a little roomier so it could be worn over it. I guess you could just order a larger size of the same thing, for that. Alternately, a Paletot or Paddock coat could be worn as less formal alternatives, but there's no finding those.
For white tie evening wear, you need a goddamned Inverness Coat. (not to be confused with an Inverness Cape.) I can find a ton of inverness capes, but no coats. they look very similar from the front, but while the cape has a full wrist length caplet all the way 'round, the Coat actually has sleeves that are split up the sides... they look kinda like a caplet from the front, but not the back. see here: http://en.wikipedia.org/wiki/File:Invernesscoat2.jpg
For my 1860s+ tuxedo gettup, though, I have a little more leeway with what's appropriate. It seems I might be able to get away with an inverness cape here, despite it being mostly country wear. It'd look a little sinister, but I kinda like that. Also appropriate might be a guard's coat, if I can find one. also, if gloves are worn with the tux, they need to be gray, not white.
gods, I need to be sleeping now.