How to use z-depth data in Fusion

Hi,
when I have an animation rendered from Maya containing two exr-image-sequences.
1st sequence: the rendered images with beauty-pass and No DOF.
2nd sequence: b/w images representing the z-depth
How can I use the z-depth data to create DOF in fusion ?
Thanks for your help.
Peter
when I have an animation rendered from Maya containing two exr-image-sequences.
1st sequence: the rendered images with beauty-pass and No DOF.
2nd sequence: b/w images representing the z-depth
How can I use the z-depth data to create DOF in fusion ?
Thanks for your help.
Peter