You could maybe create your text as a datum-curve and project it on your surface.
Then use the projected curve to trim your surface.
Another way is to extrude a surface comprising of text thru your surface and use that to trim.
Note that for some reason text isn't an option in sketcher for a surface (at least as far as 2001). A workaround is to create your text as a datum-curve and use-edge on this when creating your surface sketch.