How to enable overwrite mode?

Hello list,

a quite simple question as I assume, however, I'm looking
for an answer ;-)

How can I enable in XEmacs an overwrite option for marked regions, e.g.
if I mark a word and just type in the new, it shall automatically
overwrite the old word. Also I want to enable to delete a marked region
by pressing the backspace or delete button on my keyboard.

So, what must I do to get my XEmacs working like this. What must I
enter in my init.el?

I am running XEmacs 21.4.15 on Fedora Core 2.

Alexander