I want to drive my webdriverio tests with ChromeDriver, without going by Selenium. That should be [possible, it seems](https://sites.google.com/a/chromium.org/chromedriver/getting-started), but I am not sure where to start.

I have tried starting up ChromeDriver like this

```
chromedriver

```

and then in another Window I have started up the `wdio` testrunner like this:

```
$(npm bin)/wdio 

```

If doing nothing this will just get me

```
ERROR: connect ECONNREFUSED 127.0.0.1:4444

```

Changing the port in the `wdio.conf.js` to match the ChromeDriver's port 9515 gets me

```
ERROR: unknown command: wd/hub/session

```

I have tried adding `--url-base=wd/hub/session` to the chromedriver startup options, but it just changes the error to 

```
ERROR: unhandled request

```

Still, no go. I have set the `services` property for wdio to `['chromedriver']` - but it does not seem to take effect.