Can I use a custom ENTRYPOINT and CMD in my Docker image?

It is not possible to use custom ENTRYPOINT and CMD. 

To be more precise, neither of them have an effect when ran in Valohai. The design is such that only the step command(s) and nothing else will be executed. The --entrypoint will be explicitly overridden with an empty value and CMD will be replaced by the Valohai execution commands.