this might not be what your entirely looking for but it may give you a few more ideas on how to go about building a clock with an LCD screen!
scroll down towards the bottom(youtube videos):
http://tronixstuff.wordpress.com/2010/06/06/getting-started-with-arduino-–-chapter-nine/
also check out the "tutorials" for more clock/LCD/DS1307 stuff:
the DS1307 can be purchased as a kit for convenience!
here's the tutorial for the above:
http://www.ladyada.net/learn/breakoutplus/ds1307rtc.html
hope this helps some 