You can run multiple instances of the parser .exe.
As mentioned above, once you get the files extracted, you can create multiple folders and drag multiple .warc files into each of them. Then each time you launch the parser, just point to a different folder.
Once all of my folders have been parsed, I will usually run the parser on the main folder to auto-delete any files someone else has parsed in the meantime.
I've been running chunks of similar sized files, but PK may call on folks to proceed by file name, that way people can call out a section of files they are parsing at any given time, to minimize overlap.