An implementation of UNIX path APIs is available from:
svn://troy.wine-branches.troy.rollo.name/troy/branches/unix-path-apis
This is an SVK branch, so if you use SVK you will be able to merge it into your own branch. The implementation is also merged into the following trunks:
svn://troy.wine-branches.troy.rollo.name/troy/trunk svn://wine-branch.corvu.com/corvu/trunk
Not all APIs are implemented, rather a mechanism has been provided for specifying the interface of an entry point that is used by a tool that generates the UNIX path name entry points (it can also generate the 'A' versions of non-UNIX path name entry points).
I will put some documentation on the Wiki.