Well the article is kinda 1/2 there already: the DS1307 is a 5V I2C RTC so the
voltage level shifting section is exactly the same if you want to connect it to a rPI. If you care to read the DS1307 datasheet it's possible to write a simple shell script to set/read the time on it with the use of I2CTools ... just bare in mind that the registers are in Binary Code Decimal.
Threre is howver a really simple trick to print a 2 digit BCD number as a human readable decimal (print it as if it was Hexadecimal) ... conversion is only required if you want to manipulate the data to set the system clock.
Asap I'll add a section to that article with a bit more gory details.