how do you set up drivers in blender 25?

hey does anybody know how to make drivers for contraints in blender 2.5, like say i have an arm thats set up with both IK and FK controls and i need an arbitrary bone to control the influence of the FK and IK contraints how would i set that up in blender 25 ?

This video includes setting up drivers, not for your specific circumstance but the methodology should be the same http://www.blendercookie.com/2010/03/10/working-with-shapekey-drivers/

Nice link Richard!
Thank you!
:wink:

cool, thanks for posting the link, this certainly demistified what happened to the drivers in the new version of blender