Sure,
Take your chocolates to your barred/cuckoos, and you will get barred fawn/dun
The barring is a dominate trate and will go over most any color. Try to cross them to any color, at most you may have to take the offspring back one more time to the cuckoo, but by the second year tops, you'll have them.
As for the blues, or any for that matter, you can use barred or cuckoos, I think Ideal Hatchery has both, not sure of their quality, but pretty sure the have them both on O.E.'s
As for the how to MAKE barred's. Some one with more genetic experience than me will have to chime in on that one.
Might place a wanted post on here for them and just buy some if you have seen them already.
If making them is the only option, you may have to outcross them to a similar breed, then breed back to the moderns, 3-5 years minimum to "pure" them back to modern. It's a similar problem I am running into with the d'anver project, there's just a very limited amount of colors available in them to work with, so for some, I will have to out cross, it just takes years to get the breed back right, but in the end it's worth it. If you do go this route, just start with your absolute best moderns to start, and keep new blood moderns every time on the cross backs to avoid over inbreeding, or you will end up getting the color you wanted, but have them either sterile or very weak..
Hope that helped a bit.
Aubrey