I do a super-lazy version of "in the pot" swirling - I put some colorant in the soap pot itself, then blend it in by moving my stick blender up and down over the colorant, and then moving it back and forth in a very small area. The goal is to color about 1/3 to 1/2 of the batch. I have successfully done this with 2 colors while also leaving some of the soap white. Then when you pour, you move the pot slowly back and forth over the mold, using a spoon to pull soap from the different colored areas. It's best to use a log mold for this.
If you are using a column mold or even individual molds, you can still do this - just spoon up soap from the different areas of the pot and plop them in the mold. When the soap is in the mold, give it a single strong stir (3 stirs at the very most) to add more swirl to the soap.