Transparancy, without HTML... :)

Hello.

I will try to be brief.

I am hoping to determine if it is possible to have a transparant background in a swf without using HTML params to define it. I am fairly competent with HTML, but this does not suit my needs. I am hoping to use this in avatars etc for forums where I cannot alter the HTML housing the flash.

Much thanks to anyone who can point me in the right direction.

Cheers!