Perl-fu - transparent colour

[Gunjan Kapoor]

Hi,
Could someone help me out with this. I need to specify a transparent
colour for the entire image. Is that possible with Perl-fu. e.g: specify
white as the transparent colour.
Additionally, I need to make the background transparent for a
programmatically generated image. The image contains only one drawable.
I've tried adding an alpha channel programmatically but perhaps did not
know the proper procedure and the desired results were not achieved.
TIA
Gunjan