Step One:

Longjump from the star of the walkway so that you land on the second flower (on the floor) away from the tower as shown in the image.

Step Two:

Line up with the leaf shown on the floors flower pattern. This will allow you to hit the wall at such an angle that you land on the star platform.

Step Three:

Perform both the single and double jump on the walkway platform then hit the triple jump on the edge over the gap. (Marked on the image)

Step Four:

Try to steer towards just left of the centre of the wall (the red line in the picture). If you go too far right you will miss the platform. also make sure NOT to get a first frame wallkick

Landing exactly on this red line (in the middle) will make it more likely to not ledgegrab but also more likely you will miss

Quickest Ending:

If you ledgegrab the quickest way to grab the star is to longjump, wallkick then groundpound it. If you dont ledgegrab and still have momentum jump again and groundpound the star. If you dont ledgegrab but land standing still, do a kickjump then another jump then groundpound.

Example: