they are the 'wrong' way for a reason; it is simple to use a cheap IC chip and convert resolver to encoder sigs. going the other way has 2 major problems that prevent most people from making such a gidget:
1) encoder pulses only change sometimes, so between changing, there is no information to help make a nice sine wave so the resulting sine wave has lots of steps which make controlling servos hard.
2) most of time today when a cheap incremental encoder is in a motor, there is also ANOTHER device to give absolute information (typically halls or hall type (commutation) channels). Without this info, the resolver cannot be absolute so the motor cannot be made to commutate correctly. There are ways around this but they are either nasty or add more expense to the converter gidget making it not worth making.
Maybe someone has a Mint thing w/encoder feedback you can buy? ebay? list full part no and we can check the dusty area of the warehouse - I think we have a box with 3-4 Mint things in it... maybe others do to?
that said, if you want to investigate it anyway, one of the products we sell is this, called SC100 & SC200. check it out here: www.newall.com