So you want to change your own locks, eh?  

Things you will need:

• Keys with a different cut.  New keys will have the cuts printed into the key as a 5-digit code.  It identifies the pins starting from the keyring side.
  • Could buy a new lock set to get some.
  • An expensive option for the lazy: Schlage Original Factory Precut Keys (5 pin - C Keyway - 20 pairs)
• Schlage 40-134 Pin Kit with Snap-Tight Plastic Box - includes follower tool, and replacement pins and springs
  • There are smaller, cheaper kits available by other companies but if you have a number of locks to handle, or you prefer OEM parts, this is the one you want.
  • WARNING: read the legend carefully and be aware that both TOP and BOTTOM #3 pins are in the kit... Make sure you go for the BOTTOM #3 pins so you don't lock yourself out of a cylinder.
• A Philips-head screwdriver.  #2 will probably do.

Videos to watch:

• Re-Keying a Schlage Entry Knob and Deadbolt - basic methodology is described in this one.  It's pretty darn good and better than Schlage's manual.  I don't know the quality of their product but their videos are great.
• Re-Installing Schlage Lock Cylinder Driver Pins & Springs (That have fallen out during re-keying) - YouTube - including this one just in case you have a mishap with the top pins/springs escaping.  This one saved me.

Reference

• Schlage ReKeying Manual - includes details like how to use the key sizing tool.  But it's really specific to Schlage models and I found it more confusing than just watching video.