I couldn't figure out the syntax for doing the equivalent directly from the command line.  This doesn't work:
```bash
sbt 'set etsyFSRepoPath := Some("/Users/mwalker/development/Ivy/repository")' clean package
```

But the same sequence of commands works in the sbt console.  This is the error I see:

```
[error] Expected whitespace character
[error] Expected '/'
[error] Expected ':'
[error] Not a valid key: set (similar: test, state, target)
[error] set
[error]    ^
```

Figuring this out would make an alias a valid way of adding this setting to our config internally without requiring us to have to remember to keep an uncommitted change in the build.sbt.