Would be better just to bin the paint and get another bag.
If not, lay out a towel on a table, and put all the paint covered paintballs on it. Then get another towel and put it on top.
Now, move the towel about on top of the paintballs, like your cleaning them... Well this is what your doing. After a while they will be fine to use
Think tech pb did a video on it come to think of it.