Agricraft should work just fine, as will Mystical Agriculture, which produces dye essence that can make any of the dye types. Alternately, Forestry's bee's are simple to automate, and will generate enormous quantities of flowers. Combine with some method of auto harvest, up to and including a vanilla style water system, and you'll have infinite dyes of most colors.
ExU2's Mechanical user with bone meal on a rose/sunflower should provide infinite of that. Blue would have to still be lapis I believe. Don't know of any blue flower that does the two tall thing.
Do Botania floral dyes work? If so, you can plant the petals and bone meal them to get a 2 tall flower you harvest with shears that provides 4 petals, and grind three of them into floral dye.