Triskelions with legs and feet, like the example above, are specific to Manannan and the Isle of Man. Triskelions, like all symbols, have a poistive orientation, or can be inverted to symbolise something negative. However, the addition of the feet can cause some interesting interpretations about which way the wheel is headed. It's been debated for some time on the Isle of Man without conclusion. It's best just to choose which ever way looks best to you.
The examples below are also triskelions, and can be used to represent Manannan. There are a wide variety of ways to express this shape, which is basically just three lines that meet at one point, and fan outwards with a bend or a curve.