If you're talking about the column headers in a pivot table, then yes, this topic just came up. Here's the original thread: http://community.qlik.com/forums/p/25825/98858.aspx
With Design Grid (Ctrl+G) activated, right click on the cell and choose Custom Format Cell. In newer versions, you may be able to use Ctrl+Click on the cell. It's a pretty cool feature I knew nothing about until a few days ago.