Not at all, you simply select the menu option. But as Peter said, you might not need to. See if it works without needing to force it first.

When I wrote this FAQ entry, I didn't say anything about Emplode being disabled for car mode, so my money is on it just working.

If you want Hijack's HTTP server and Hijack's FTP server to work in DC/Car mode, then it's likely that you'll need to tweak config.ini so that they work in DC/Car mode. But not everyone needs those features at all, let alone in the car, so that might not be a factor for you.