I would start him off with a low % equity and no (or modest) salary but retain him in a limited capacity as simply managing the off-shore development team. If you are already doing this yourself, it is not a full-time job. What you need is his expertise, not necessarily a lot of his time.
Giving him a bit of equity for his minimal time commitment is more than fair and allows you both a 'trial period' without making a huge commitment financially. When management of the product becomes more complex and requires a larger time commitment, hopefully either he will believe in the business enough to trade some salary for equity, or you will be in a better position to afford to pay him his market salary.
I agree with what people have been saying about treating each situation individually. In my case, I would not work as a CTO for equity only simply because I am not in a position financially to do so. That doesn't mean I am any less committed to my work, it just means I have a family to support / other obligations.
Just remember, it's not a 'all or nothing' proposition.