The SmalltalkImporter>>createMethod: need as parameter acompiledMethod which is evidently a MethodNode since RBMethodNode do not implement the methodClass which is invoked in createMethod:

So, am I missing something? Should I use another parser other than PPSmalltalkParser?

I think SmalltalkImporter is coded to pull the code directly out of Pharo/Moose - that is, Smalltalk code already in the image, so it uses MethodNode. Since you are not actually loading it into Moose in a runable format, but instead parsing it, you don't have MethodNode.

I think you should extend RBMethodNode with the methods that are needed to satisfy SmalltalkImporter - this will make future handling of other Smalltalk sources much nicer.

yes if someone publish code I will have a look and see how we can integrate it.