preseed late_command for dapper

[Carl Karsten]

Now that base-config is gone, how do I run commands like I did with 
base-config/late_command ?

I want to do:
echo send host-name \"$(cat /etc/hostname)\"\;  >> /etc/dhcp3/dhclient.conf

Which may need to be:
echo send host-name \"$(cat /target/etc/hostname)\"\;  >> 
/target/etc/dhcp3/dhclient.conf

^C