The Python interpreter code uses a considerable number of features that are unavailable in the current Open Watcom release (version 1.9). Specifically, this earlier release is missing a few Windows API declarations and some C99 functions that MSVC includes. Lightning Python could contain the necessary patches to provide compatibility with Open Watcom 1.9, but there would be considerably more patches. If the primary goal is to convince the core Python developers to reinstate Open Watcom as a supported compiler (unlikely), the fewer necessary patches, the better.
Obtaining Open Watcom 2.0
A fork of Open Watcom is currently maintained that addresses some of version 1.9's shortcomings. The port is hosted at GitHub. In theory, anybody could download and build this version on an assortment of host operating systems. However, building Open Watcom is somewhat complex and extremely time-consuming (it requires hours on even modern hardware).
There are two locations where the binary distributions can be obtained. Standard installers can be obtained from:
I would suggest downloading the x86 Windows C compiler. The 64-bit builds are experimental currently, and Lightning Python only supports the 32-bit target at this time.
Alternatively, nightly builds are available from:
The nightly build generally work fine.