PipX is a standard library, providing general-purpose steps. Its is written in standard XProc 1.0. It does not depends on any vendor-specific extension. Some modules might depend on EXProc extensions in the future, in order to provide tools for them as well.
PipX has been written as one single XProc library file. You can download and install it as a XAR package, available from the PipX entry on CXAN.
If you do not use the EXPath Packaging System, you can download the library file from GitHub and copy it to your project.