The timer is just an external program called LiveSplit. The rules state specifically not to use any plugins, so I think it's probably not allowed.

Edit: After looking a bit of runs, it does look like some use an in-game timer plugin. But, I'm still not really sure about zombie counts.

Possible 5-6 hour run will take a while for the mods to verify. This site itself tells you that verification could take from 1-3 weeks, so I'd go with that.