It is something I have always done using the following code. I can enter actual time (0-23) and date values (0 to 31)
i2cslave %11010000, i2cslow, i2cbyte
hi2cin 0,(SECONDS,MINS,HOUR,DAY,DATE,MONTH,YEAR)
BCDTOASCII DATE,DATE_T,DATE_U
BCDTOASCII HOUR,HR_T,HR_U
BCDTOASCII...