Opportunity is missed by most people because it is dressed in overalls and looks like work. - Thomas Edison
I'll actually be using the unlined ones, so hold down won't be an issue. Do you just print these wet on wet? I'd imagine flashing isn't a great idea.
You will need some type of hold down device and you have to flash between colors. Use trap registration to resolve misregistration issues due to the substrate shrinking under the flash. Read over the link for more info... http://www.iccink.com/pdfs/Nylon%20Direct%20Print%20How%20To's.pdf