Yeah I emailed sloth about getting the frame ano'd on an ion and the reply was; We can indeed anodise, however ion frames as far as im aware come powdercoated, and there for cant be anodised unless the powdercoat is first removed. Unfortunatley this is not a service we can currently provide, but It is possible (though not simple) to do yourself. I believe there are some pretty good instructions on pbnation.com in the forums.
Not sure how to do that myself so needless to say I gave up within reading it lazy would be the word hope this helps.
FatTart o/
if you didn't want the hassle of doing all that however; then you could always buy a new frame from fireball mountain or other shops that do the same thing, and they'll do the custom anno'ing too, so when you recieve it, it'll be new, different and totally personal... this is the page to all their products but the best ION frame is the one that is based on the Ton Ton shocker frame, this one... just giving you another option and they aren't that expensive either.