How do I do this?

[Kagamin via Digitalmars-d]

dmd has a feature that a file passed directly to the compiler 
overrides file system for module search.
reallogger/impl/pluglogger.di
---
module mylogger.logger;
public import reallogger.impl.logger;
---

main.d
---
import mylogger.logger;
...stuff
---

dmd main.d - imports mylogger/logger.d
dmd main.d reallogger/impl/pluglogger.di - uses reallogger