Thanks Dimiter, that is helpful. However, I don't think that I was clear enough in my question to communicate what I really need.
I am trying to accomplish the following:
* Show the up/down glyph to indicate that the column can be sorted (which was answered)
* When the column header is clicked, instead of showing the native up and down sorting arrows, the column header should contain the glyph up and down arrows (k-i-arrow-60-up, k-i-arrow-60-down)
Is there also a way to replace the sorting arrows that are native to the grid?