You can get any girl to do anything, actually, so long as she's really into you.
I don't mean to seem like I'm some sick bastard, though I've did my fare share of things (nothing involving my ass hole or poop, ugh!,) but one day me and my then fiance were a little drunk, and I was like "shit I have to pee, hold on baby,) and she offered to drink my piss, I was like "wtf!?!?!?" and let 'er rip, it was the single most awesome thing I've ever experienced.
In conclusion, I think you just got to meet someone first, get in good with them, then slowly bring upon the "what would you do" questions.
Go to Brazil.
I realize I'm responding to a somewhat old post - but anyway here is my advice.
Girls or women that are already into an extreme fetish are usually pretty messed up emotionally
and are already in godlike positions within their fetish communities.
If you want one, your best bet is the relationship route.
Find a woman (nationality is irrelevant) who is open to trying out new things, and slowly work them up to where you want them to be. As long as you make her feel safe and comfortable, you'd be surprised at what you can get a girl to do willingly, and eventually to enjoy it just as much as you do if not more.
To make your task easier, go for a girl with low self esteem, low self confidence, and is eager to please and be accepted. That will make your task easier.