I wish to use a custom avatar

[Peasant Phill]

Ancillaries... Now thats one large pool of cool pics to go through, good idea

Simply put:
Get a TW portrait
Make it the right size
make a (not so) subtle change to it
Put the correct frame around it

Then there should be little to no reason to deny you a custom avatar.
(I added a smirk in my avatar)