use autotext .. example i have like "pcnetsig" with my signature info.. at the end of a message i enter pcnetsig -> enter and my make-shift sig is inserted via autotext..
hope this helps .. i found this from the tip & tricks thread.. has proved to be very helpful .. if you also have BWC you can do it from there also (i think).. but since i have multi-email address coming to my BB this works just great in conjunction with BBreply