Paste into Layer Mask in Painter - anyone succeeded in doing this?

Hi,

I've exhausted everything I can think off to paste a grey scale image into a layer mask.

I've tried these methods outlined here http://painterfactory.com/painter_product_discussion/f/79/t/23502

if I " duplicate layer and go to Layer -> Create layer mask from transparency" - it doesn't work because there isn't transparency in the image I am tying to paste, just grey scale

I've tried pasting into the mask via the channels window - but it just makes a new layer .

I watched Jason's excellent video on the Channels palette - but didn't pick up any clues how to solve it

thanks for any advice....

or is it impossible in Painter?

(hope it's okay to start a new thread on this)

cheers from Oz