Total fail of mysql gem with ruby 1.9.1 on Snow Leopard

[Doug Livesey]

Hi -- I have a 64bit install of MySQL (from the DMG installer) that is working fine with Ruby 1.8.7 -- I have the mysql gem installed for that.
Now I have installed Ruby 1.9.1 (with rvm), and cannot for the life of me get the mysql gem to install.
The output from one of my more comprehensive attempts is here: http://pastie.org/658627b
Basically, I'm getting the same error no matter what I try.
Can anyone please advise on what I should try next?
As far as I know, my install of MySQL should be fine, and everything else seems to be -- it's just this that won't work.
Thanks for any & all assistance & advice,
Doug.