Chronos depends on gproc and has been tested with 0.2.12 as well as the latest master (b1855cb88 - as of 2012-02-25) after the 0.2.12 tag.
So you have to install gproc-0.2.12 in a place where your Erlang can find it.
Just add dep_chronos = https://github.com/lehoff/chronos v0.0.5 to your Makefile and it should be fine.
If you are using rebar to build your project you should add the following to your dependencies:
{chronos, "0.0.3", {git, "git://github.com/lehoff/chronos.git", {tag, "v0.0.3"}}}
Chronos uses gproc and should you run into trouble with the gproc
dependecy Chronos will probably just work with the lastest version of
gproc, if not, please let me know and I will look into it.