There is no magic formula, but it's generally fairly simple to flip a sock around.
With many patterns, you simply need to know how many stitches you'll need around the foot and you can adapt from there. You work your favorite toe to that size and then begin the pattern, but beware, cuff down socks with a one way pattern (for instance lace) may look wonky worked toe up. Generally, you work your toe up sock until the sock fits all the way up the arch of your foot and you've hit your ankle. That's the point to start your short row heel. After completing the heel, you can continue in the pattern, reversing the instructions for the cuff down exluding anything about gussets and heal flaps.