I have been unable to look up how to set date/time for years on this old system. I found my cheat sheet I made from a post I found here 18 years ago!
In the interest of the other person still using these I thought I should put the info back where I found it. Hope that is OK.

From station 10:
# * 51 YYMMDD # to set date
# * 52 HHMMSS # to set time
# * 53 D # to set day(1-7)

Seems to NOT be in the 150 page setup manual nor anywhere I could find online now! Looks like it should still be here but search doesn't work.