For the moment, there are no way to do this from Pegasus version 2, but there is a way to achieve this from Pegasus version 1. Follow these instructions:
1. Create a signature in Word or your favorite editor, and Save it as an html file:
2. Login to Pegasus version 1:
3. Upload it following this path: Appearance -> Mail Signature
4. Select the file you created in point number 1, and click on “Save Button”