DSL Embedded :: booting into root....bad

i am using dsl on a usb pen drive. i have just unzipped the embedded zip to the drive and i run the dsl-linux shell script..i have password protected root and added users. but on reboot i just boot right into the account with access to root shell..all accounts and permissions are still intact..is there anyway i can use a boot loader like this installed to an mbr on the pendrive or something?

or password protect pen dive partition? i need to have a root account but i also want others to be able to use the drive just not modify it. thanks for any help

original here.