You can silkscreen with Bare Conductive's conductive ink (they're coming out with one that is specifically for fabric, but you can still try with the regular stuff): http://www.bareconductive.com/
There is solderable conductive thread out there, though I havent had the pleasure of trying it: Solderable conductive thread
And also there is stretchy wire, which I have seen (it's super cool), but havent used: http://www.mnwire.com/istretch