Not all cells are collimatable with push/pull screws - that's something you need to find out first. If there are no screws, it is a much more involved job if you want the optical axis and the physical axis to align. Everything is done at the focuser and the cell mounting at that point. Leave that to those with a proper setup for that.
A triplet and doublet with collimation screws are no different to collimate in cell tilt. Centering a triplet (getting the individual elements aligned with respect to each other, not just the tilt of the combination) is much harder than centering a doublet and you should NOT attempt that unless you know what you are doing (it's microns of precision).
With push/pull screws, it's a fairly easy task. You first align the focuser to the physical axis. Place a laser in the focuser and have it hit the center of the objective (as noted with a template with crosshairs on the cell). Make sure it still hits that target as you rack the focuser in and out. The laser itself needs to be colimated for this to work. Next, you use a chesire eyepiece to get the reflections off the back of the various elements to all line up concentrically.
The reflections are different sizes, so blocking half the chesire window with a strip of paper and rotating it around the winidow helps to see whether the differently sized reflections are concentric. You get semi-circles instead of full circle reflections that way. Rotating the strip helps determine which screw to push/pull. It also helps to have a pair of close focusing binoculars to make the reflections look bigger. 2.5x monoculars come in handy for this.
All you need are a collimated laser, a template for the objective, a chesire eyepiece (preferably without crosshairs becuase they get in the way), a strip of paper, and prefereably some kind of magnification device to make the reflections look bigger. This gets you on the pitcher's mound of the ballpark when you finish by tweaking the collimation on a star in good seeing. If the cell does have push/pull screws, it is worth knowing how to do it. As with all fairly easy tasks, it's easy once you have done it a few times.