To create gradient text in corona, you have to download ‘Corona daily build 612’ which has functions like setFillColor() etc. You create a new gradient object by calling graphics.newGradient(). You can pass (and reuse) the object in calls to text:setTextColor() and rect:setFillColor(). Here is an example.
This is really simple in Corona, just use textObject:setTextColor( 255,255,255 )