I'm not sure what the problem is.
In Office XP's Word and using the Draw toolbar, I select the straight line tool, draw a line, then select the straight line tool again and draw another line at right angles to, and touching, the first.
Or am I missing something from your post?
How can I change direction (i.e. make a corner, and preferrably a 90 deg angle)when drawing a straight line in MS-Word?