There is an Rcs wrapper module in CPAN called Rcs which worked well for a group I was working with. Part of our task involved controlling certain rcs activities through a Web browser. There were at the time a couple of bugs and misfeatures that we worked around by subclassing Rcs and replacing or wrapping some of it's methods. I notice that the CPAN module has been upgraded since then, so some of those problems may have been addressed. One issue you'll need to be concerned with if you are coming in through the Web is user identity. When coming in though a Web server all rcs checkins will be recorded as being done by your web server user, not the user that is on the other end doing the real work. The same is true for any locks that are obtained and any access restrictions based on username. We overcame some of the problems -- engough that the system worked for us -- with some hacky slight of hand with user session information (our users had to authenticate in order to do rcs work) that the server collects. IIRC, it involved creating a special branch off of the initial 1.1 revision that was tagged with a specially formatted string that included the real users name. As I said, it was a hack.

There is another more complex Rcs interface in CPAN, VCS::Rcs. I have never used that one, but it might be worth a look, too.