OCaml support is now in CTags svn repository accessible here :
svn co https://ctags.svn.sourceforge.net/svnroot/ctags ctags
It will be released with CTags 5.8 which should be released soon (within the month). CTags can be downloaded on his website. The final version of the parser is cleaner in it’s output tags and their contexts, and is fully usable with vim and the taglist plugin.