this question is very similar to this: Using Vertex Shaders in Materials - question - Forum
and I am working on an example that demonstrates how to set this up properly but it got delayed by more important bugs that need fixing. i think it will be ready by the end of the week ahead.
however, if you are really brave, download the latest preview, it has a WIP state of the example in it. it even works, but it is still experimental and needs improving. so don’t tell anyone yet…