Hari's Z-Wave device is a DCE device, and thus should be used within the construct of DCE.
...or, you could just reinvent the wheel like any other programmer...but in my view that would be retarded.
A quick look at the code shows that ZWave.cpp seems to implement the "DCE" interface needed by LinuxMCE, while ZWApi.cpp implements the Z-Wave primitives and actual interface to the USB device (via a serial library).
So it seems quite probable that these two pieces could be split, and thus avoiding reinvention, as well as the need to provide a lot of support infrastructure that may not be needed by simpler projects.
I ran across discussion on the MisterHouse list about how some of the developers aren't happy with the MH driver architecture and they mentioned the idea of using xPL/xAP as the API:
which appears to be a community developed protocol designed to layer over proprietary automation protocols, such that you might have say a gateway box (or daemon) that talks Z-Wave, and another gateway box that talks INSTEON, with both connected to Ethernet and speaking xPL/xAP to the main controller.
The LinuxMCE driver could then be split into two components: a DCE wrapper around an xPL/xAP client, and a Z-Wave driver that implements the xPL/xAP network interface.
Then HA software in any language can interact with your Z-Wave driver, and you can gain contributors to it from multiple projects. Plus LinuxMCE gains access to other xPL/xAP devices.