Newbie needs help with postinst scripting

[Arne Goetje <20020531antispam@gmx.net>]

Hi list,

I want to make a debain package for a collection of perl and php scripts 
for my company. They will not go into public.
In my case I need a postinst script that asks the user for the local MySQL 
server password and then puts the command string according to that (if 
empty, then no -p argument). I'd like to have this nice user interface that 
some packages have ( I assume, it uses 'dialog'... ?).
However, I don't know how to do that in the script (normal shell script) 
and I don't find any documentation. Can anyone help me or point me to some 
documentation on how to set variables through a user interface with a 
password dialog?

Thanx for help.

Arne