No I think that item is fixed with the standard chat display timer.
( or alternatively - i don't know that it's possible to change it. )
Something else you can do to make the messages stand out more from the regular player chat is to change the font color. It draws their attention. You can do that in your rss.ini by adding a text colour line. I use white. I edited the rss.ini section in the above post for an example.