If you really need Unown for your next great Emerald Battle Frontier team and you're already familiar with FR/LG RNG abuse, fine, here's how I did it:
Step 1 is the easy part, generate a bunch of method 1 spreads with the IVs you want (ignore nature, we'll get to that next).
Step 2 is more annoying, go through the spreads and figure out the new nature it will get when the upper and lower halves of the PID swap, if you've got a program to do this or even one that can find BACD method spreads go ahead, otherwise open your favourite calculator program and
get to work, do this until you find one with the nature you want (Adamant, Docile, and Gentle are all very good natures for something that is already as useless as Unown).
Step 3 is the most important one,
figure out what Form the PID results in, once again you can use a program to do this, but a calculator and notepad works fine too. An important note about this step, from my small experience the link has ? and ! Unowns mixed up, they also seem to appear much less frequently than the normal letter forms, so I would avoid any spreads that result in either of them.
Step 4* is probably the most time consuming, grab your Sweet Scent slave,
go to the correct chamber for the Form you got in step three, and get close to your target method 1 frame (this depends a bit on the mon you use for Sweet Scent, but with Oddish I've found ~300 away to be a good place to start, assuming no frame skipping).
Step 5* is the most annoying, check every frame until your target spread is past your Sweet Scent delay (~260 for Oddish), you might encounter your target or you might not, I have no idea how the RNG decides which spreads it likes, other than skipping any that don't work for the location you're in.
Step 6, brag about how much time you wasted RNGing a useless Pokemon on an emulator!
*For steps 4+5 doing a "trial run" by editing the current RNG seed in the memory can save a lot of time waiting for a spread that might not even work, but this isn't really RNGing and Pokemon obtained from this method can't be traded here on Smogon.
Don't ask me any questions about how to do this, if you're still having trouble go back and read the first two spoilers.