Virtual grid and RichText formatting

HI,

I have a readonly virtual grid (contains a single column) which displays all the strings that match search criteria. While displayign thses strings in grid I would like to highlight(using a different color) the seach pattern in the matched strings. The pattern can appear anywhere and multiple times in a string and all such occurences should be highlighted. I understand that I can use RichText cell model. But What do I set the rtf/text to, so that the desired behaviour is achieved.
Kindly let me know. Thanks.

Regards
Kiran