<owner> <question> <type> <value>

my-package username string Bob
my-package password string I$aN1ceGuy

debconf-get-selections | grep my-package

debconf-set-selections <filename>.
dpkg -i my-package

apt-get install expect

#!/usr/bin/expect -f
set timeout 30
set password "pass"
set username "user"

#run the command
spawn dpkg -i package.deb

# Look for username prompt
expect "*?sername:*" #<--- this statement is important it wait's for a prompt "username:"
send "$usernamer"

# Look for passwod prompt
expect "*?assword:*" #<--- the same with the "password:" prompt
send "$passwordr"

#dpkg -i continues