Libxml2 is the XML C parser and toolkit developed for the Gnome project, libxslt is the XSLT C library developed for the Gnome project (but both are usable outside of the Gnome platform).

Libxslt should be recent enough (version >= 1.1.13) to support plugins. Check also that development headers for libxml and libxslt are installed.

If your libxslt installation doesn't satisfy the requirements, install a private version of libxml and libxslt. Download tarballs and install the programs as usual.

$ tar zxf libxml2-X.Y.Z.tar.gz
$ cd libxml2-X.Y.Z
$ ./configure --prefix=$HOME/opt/libxml
$ make
$ make check
$ make install
....
$ tar zxf libxslt-X.Y.Z.tar.gz
$ cd libxslt-X.Y.Z
$ ./configure --prefix=$HOME/opt/libxslt \
  --with-libxml-prefix=$HOME/opt/libxml
$ make
$ make check
$ make install