The method I use is pretty simple and probably not what you are asking for – but I’ll tell it anyway.
I make the bug, collapse all the visible layers into one, use the magic wand to select everything around it, select the inverse, go to the channels tab, click on the “save selection as a channel” box at the bottom. This saves as “alpha 1”. Click on the new channel and the bug should be in a white sillohuette (i think i spelled that wrong) on a black background. Save as a targa file.
I hope it helps.
Shut the **** up, Donnie