I do indeed mean soaking in water. I wet stitch my stuff, and even if the dye work is a little splotchy at the start, by the time I'm done stitching, after repeatedly submerging my piece, the dye is a lot more evened out.
I also use almost exclusively the old Fiebing's Dye. I have found that the new green label Fiebing's acetone based dye migrates much more when the leather is soaked in water.