md4coll is an MD4 collision generator. It will not find your password, what it will find is other words(plaintext) that will generate the same md4 hash. Google 'md4 collision', or better yet, take a look at the Wikipedia's entry for MD4. As for cracking MD4 hashes, I also have not seen an MD4 plugin for John, however there is a utility called MDCrack(also on the openwall site) however it only runs on Windows. There is another utility called Lepton's crack which can handle raw MD4 hashes and runs on Linux, however I have never tried it, nor do I know anything about it.