Add user field to display_template

[Kevin]

I want to add a smarty assign to the display_template function. I want to
add the user's from fax number so that I can add that to the header
template.

I added $smarty->assign('FROM_FAXNUM', $USER_FROMFAXNUM); and set it to a
dummy value earlier in the function for testing on the template.

However, as hard as I try I can't figure out where I should set that value
to the user's fax number.

I tried to follow the same methods that $USER_FULLNAME get's set to the
user's name but I got lost in the code. Could someone please give me a
little help in the right direction?

thanks!