Adding xdocdiff plug-in to WinMerge Portable (v2.12.4)?

Ultimately my goal is to be able to use WinMerge portable to compare two PDF files. I couldn't get it to work in either the desktop or portable version intially. (I would get a screen full of "gibberish".)

I was able to get it working in the desktop version by installing the xdocdiff plug-in.

What I was wondering was if there was a way to install this plug-in in the portable version?

I tried copying the xdoc2txt.exe and zlib.dll files to \WinMergePortable\App\WinMerge and the amb_xdocdiffPlugin.dll to \WinMergePortable\App\WinMerge\MergePlugins, but it didn't work as far as I could tell.

It could easily be an error on my part, but before I got started tracking the problem down, I thought I should first find out if what I am trying to do is even possible. (i.e. if plug-ins from the desktop version can be installed on the portable version.)

Thanks for your help!