I am trying to setup a central repository with shared hosting. I read all the way through this tutorial https://www.mercurial-scm.org/wiki/PublishingRepositories to no avail
I had the same problem. I needed to set up a Mercurial server on a shared host to which I do not have root/shell access. I followed this guide and with surprisingly little frustration, got it to work:
http://javadocs.wordpress.com/2010/04/27/set-up-mercurial-1-5-1-on-a-shared-host-simplified/