Human form for non-Great dragons, Is there a RAW way? Options

[HugeC]

So I've been mulling over the idea of an SR4 campaign, trying to come up with NPCs to populate the story. I thought a dragon or two would be neat, but I'm wondering how such a creature is supposed to be a mover and shaker in metahuman society when it can't take on human form. Since I plan for these NPCs to be potentially killable by PCs, I would rather not populate my world with additional great dragons.

My first thought was the (Critter) Form spell, but it is out because it says the average Body of the form you are taking has to be within 2 points of your own Body. Even a troll's average body is 7, which is much too low. Anyway, it seems to me transforming into a metahuman violates the spirit of this spell.

I don't have Street Magic; is there a way for a custom spell to transform a dragon into a humanoid form? Or are all transformations like that limited by Body?

Also, why is it that drakes have a metahuman form (at least, I gather that they can from reading this forum, I don't have RC yet), and great dragons do, but the 'regular' dragons can't? I suppose if I am the GM I can just say, "Even normal dragons get human form, so there!" I'd rather follow the published rules, tho. Any ideas?