If you load one of the mask images that came with AlamDV2 you will see that it is a White image with a thin black box around it (don’t know why…can any one expand on this?).
Make your mask shape on a new layer, white for masked area, black for unmasked area.
Copy that layer into a new alpha channel, delete the layer you just made.(not the alpha).
A mask is just this white image with thin black box, with the detail only in the alpha channel.
Name is mask_yournamehere in the Plugger.
Hope this helps.
Ps don’t know if just a white image works.