Question
I just want to meet him for a quick coffee (I know time is valuable and when visiting from another country, these kind of people are generally open) and I do know some people that know the person I want to reach out to, but I don't know how to ask them.
Answer
Have a read of this excellent blog post from Noah Kagan (ex-Facebook, Mint, high-profile blogger) on exactly this topic:
http://okdork.com/2013/04/18/cold_email/?hvid=O3hU5
He goes through in step-by-step detail a real email someone sent him asking to meet for a coffee and explains exactly why it worked and how you can replicate it.