Switch to Configurable USB loader. Set simple mode to 1 and set a password.
You CAN autoboot to a forwarder. But u need to have the actual boot.dol in the appropriate folder either on SD or USB. Get a config usb forwarder, load it. Set your autoboot and return to to installed file. Done.
I'm working on a parental controls guide as time allows, which will cover all of this and then some. Not quite ready yet.