Scroll box to follow text to bottom.

Hey,

I am running a TCL script through the system() function in php. Its
output is to a scroll box I put on a web page using DIV tags. Its all
working fine expect the scroll box puts out the text and gets very
big, very quickly. I would like the scroll box to follow the text
[i.e. lock to the bottom of the scroll box] as it is put out from the
script.... but don't know how! This should look more like the user is
watching it in a terminal window.....

Any help would be appreciated!