Transparency in images

Hi
There is something I'd like to achieve but I don't know if it is generaly possible with Hypersnap.
If I select an area in a capture with lasso and then do a copy/paste into a secondary capture, is it possible to set for the pasted image a transparency value so that get a "ghosted" look in the second capture as result?
I know that I can do trasparency for some selected colors with the  substitute function but then just a specific area is done with transparent color. What I'm looking for is transparency all over the whole image. Ist that possible?
Thanks in advance for help
regards
Alex