How to get parameters from a class inheriting VariableFunctionBase in v4.9?

Using Buildmaster v4.7 and earlier, I wrote a custom extension inheriting VariableFunctionBase in which I could define my custom parameters.
It was then possible to get the values from the Evaluate method using params [] args.

We've upgraded to v4.9 which means this approach doesn't work anymore. Any custom extension inheriting VariableFunctionBase needs to use ScalarVariableFunctionBase meaning the Evaluate method has now become EvaluateScalar and no longer takes the arguments.

This link is no longer true as of v4.9 - http://inedo.com/support/tutorials/writing-a-variable-function-using-the-buildmaster-sdk

Trying to find something equivalent for 4.9, but no success....

Product: BuildMaster
Version: 4.9.7

The tutorial still needs to be updated (we will do this for v5), but take a look at the SDK Documentation for how the variable base classes work now; basically you declare them as properties and then use attributes to indicate that they are parameters.