Alternately you can hit <CTRL-Z> when the boot sequence asks you for the date and create an account using:
RUN ACNT or RUN $ACNT
(Numbers below 10 {oct} are privileged)
Reboot and wait for the date/time question. Type ^C and at the MCR prompt, type "abo at." You must include the . dot!
If this works, type "acs lb0:/blks=1000" to get some swap space so the new step won't wedge.
type " run $acnt" and change the password of any account with a group number of 7 or less.
You may find that the ^C does not work. Try ^Z and ESC as well. Also try all 3 as terminators to valid and invalid times.
If none of the above work, use the halt switch to halt the system, just after a invalid date-time. Look for a user mode PSW 1[4-7]xxxx. then deposit 177777 into R6, cross your fingers, write protect the drive and continue the system. This Will hopefully result in indirect blowing up... And hopefully the system has not been fully secured.