How would AML techniques work in Ripple?
AML is only applied to customer relationships. In this case that would be people that have an account with a gateway and are using said account to either deposit or withdraw massive amounts of money/crypto from the gateway. 

It cannot apply to rippled balances, as you don't need to provide any information to another entity in Ripple in order to extend a trust line to said entity. I.e. there is no customer relationship in that case.

All of the above is AFAIK and IANAL.