Some updates:
I have my TPIC6B595 registers wired up to some small 7 segment displays. I have tested them with a sketch that I downloaded from Nick Gammon's site Gammon Forum : Electronics : Microprocessors : Using a 74HC595 output shift register as a port-expander and all of the segments light up, so I know everything is wired up correctly and working. Hard to see, but I have a capacitor across the + and - for a decoupling capacitor. I also just used 1 resistor per display, since I didn't have 42 resistors for each led segment, so it does dim as more segments light up.
Now, my question. Are there some code samples/examples on how to display numbers onto my 6 digit display? Previously when I was using the Embedded Lab SPI 7-seg display http://embedded-lab.com/blog/?p=6862 the code was very simple. Like:
#include <LedControl.h> // need the library
LedControl lc=LedControl(4,3,5,1); // lc is our object Pin 4, 3, 5 and 1 display
clockminute = minute();
clockhour = hour();
lc.setDigit(0,6,clockhour,false);
lc.setDigit(0,3,clockminute,false);
Where I used lc.setDigit to send the display what number I wanted for my hour, minute, second.
Is there a similar Library for using 595 shift registers? Also, should I be using SPI.h or ShiftOut() to update my display? (I've started reading a bit about each)