use MDX

Code:
on *:dialog:<dialogname>:init:*: {
    dll $mdx SetMircVersion $version
    dll $mdx MarkDialog $dname
    dll $mdx SetFont $dname <ids to set to font change to> -<font size> <400 or 700 (700 == bold/ 400 == normal(idk any others))> <font>
}