I found it helpful to configure the hgrc file within a repository (so <repos-dir>/.hg/hgrc) with auth info. Specifically, adding
the following sort of section:
Where "something" , "appropriateusername", and "appropriatepassword" should be filled in for your case.
It seems there's a relevant posting at StackOverflow, so here's a pointer to that: http://stackoverflow...sword-with-mercurial
(The top response had a pointer to a page from http://hgtip.com/
which seems like it might be generally handy.)
May be Gothi[c] can scold me if this sort of set-up is a no-no
(I'm using mercurial through an upgraded installation of an old "portable" cygwin.)