I’ve come across a couple of patterns that call for these, and my question is do they exist?
Based on this gauge I would think you could use the size 3 and be just fine. Or the 4 if you are a tight knitter.
My Size 2 Addis are 3mm. The new Knit Picks circs also has a 3mm/US2 size, and they’re much cheaper! 
http://www.knitpicks.com/needles/Needles_list.aspx?dgroups=‘KPFixedCables’
I added that set to my wishlist. Now all I need is some money :o)