How I built my sig / avatar combination:
Took an in-game shot of the I-DN, at green alert, before the hardpoints started filling in.
Used Photoshop (although paint or any other graphic-editing program will do) to cut out the wireframe (avatar) and ship itself (sig)
Rotated ship 90 degrees clockwise
Pasted the ship itself onto a larger black field, then used the text tool with various fonts to insert my name / information / quote etc.
Put final image onto webspace, sig was born...
Resized avatar to Taldren's pixel specs, uploaded that, and the avatar was born.
Took me an hour or 2 to do it. It would probably take me a lot longer if I went with a more involved background, but being partially colorblind I went with simpler colors so I could see what I was doing...