If you are trying to print halftones in photoshop you just have to convert to bitmap and during that process you choose frequency shape etc. I do not use a rip and do gradients and blends all the time using this method.
You will need to have your colors sepped and print ready (trapping etc), then grayscale and flatten each color in its own file, then do the conversion. Once converted, switch back to grayscale, select color range, click on the black areas, create new layer, then duplicate into a new file. Do this for each color so you have all your seps in one file. Then duplicate your original sepped layers into this file. Now if you have to make adjustments to particular layers down the road, you just duplicate those into a new file and repeat the process after making your adjustments.
