Custom Signature in Entourage?

Hello,

I am trying to set a custom signature in Entourage for an iMac. I have a .htm file codes that utilizes image/text. In Windows environment I would just place the coded .htm files w/ the necessary images in the signature folder. On iMac I am not sure if I can do this, or just copy the actual code in the htm file to the signature creator in entourage. any help is appreciated.

-JT