Portable Method of Deploying Oracle Express on Windows (Ideally without Installer)

I'm looking for a portable way of deploying Oracle Express alongside a C# application on a continuous integration machine running CruiseControl.

Ideally I would not have to use the installer - this machine is being used for building a lot of other projects, and we are concerned that running the installer could break something. Ideally, the database is wholly contained within the build folder, and this build environment would be completely separate from any other builds or programs. We don't like things that are global to the whole machine!

From what I can see though, this appears to be impossible. Oracle Express runs as a service, which puts it at a global scope. Is there a way that I make it local? ie. I run an executable to start and stop it, and it has no dependencies outside the build folder?

If not, what would the effect of running the installer be?