I was doing some automation and auto bootstrapping of CPAN, but since I was creating configure and enviro bootstrap scripts to set up an environment for a Java application on n hosts, I elected to use PAR to bundle the scripts into executables that can be deployed to hosts fully formed with modules installed and a standardized version of Perl included, if need be.
What in particular is the application or script or suite of scripts that needs these modules installed? Is automation of CPAN install really desirable when you don't know the version of Perl on these hosts? In the case of that kind of heterogeneity, I would go with PAR. Unless, of course there is some compelling reason to work with CPAN auto install.