Add custom symbols to dimensions using the Symbols palette in Creo 9

I have created custom symbols and added them to the Symbol Palette (draw_symbol_palette.drw) and it works correctly.

What I would like to do is add the same symbols to the palette that appears when you modify a dimension, for the Dimension Text symbols.  You have many symbols available and you can manually add the symbol to the dimension. Example: "@[xx@]" will give you 'xx' in a box.

The reason to add it in this location is so that when a tolerance is added, the symbol will automatically move out to the correct location and for ease of use for the users.