You can use Photoshop to control tonal values in the art. This saves more data IMO. The RIP can do it as well but I notice a loss of information on film output. There are multiple controls in the curve dialog. There are 3 eyedroppers below. One for black point, one for grey point, and one for white point that my artist used to first adjust the image. Then you can grab the lower left corner and move it. Watch the input and output boxes. Input could be 6%, but when you grab the lower left corner of the diagonal line you can move it to the right and make output 0% for an input of 1,2,3,4,5, up to whatever tonals you want to output at 0.
Someone mentioned how to use the eyedroppers in another post. But basically by setting the white point you eliminate having any values appearing in white and results in 0% tonal in the white background. Doing it for black keeps 98-99% tonals from appearing in solid black areas. There are others here who can advise better on the curve functions in Photoshop.
For Wasatch the linearization is for film, the second for press adjustment. Dot gain on press can also add 20% and completely close in 70-90. A reflective densitometer is needed to apply a second linearization. Or you can manually adjust and experiment here. Quite often tonals above 60 can be massaged to stay open on press better by estimating dot gain in these areas. Press set up, and squeegee parameters need to be duplicated, linearization doesn't fix tons of squeegee pressure.
For most common sim process on blacks the punch contrast and other auto adjustments in Wasatch in combination with linearizing film output can produce very nice prints.
Once you have dialed in your linearization make sure to save all your hardwork. You can have several depending on line count, angle, shirt type, etc.