Here is a beginning of a rcs plugin that uses rcsmerge, rcs, ci, co and rlog. I have used it probably over hundred times but needs some work.
Clearly needs some cleanup and perhaps some of the missing stubs implemented, before it can be included into ikiwiki.
Notes on individual functions:
rcs_prepedit - I'm not sure why you do the locking since the comment notes that the locking does no good..
rcs_getctime - You ask why this would be better than mtime. It's because with something like subversion, a file's modification time or ctime is not necessarily accurate WRT when the file was first checked into the repo.
Also here is a quick script to browse the RCS history to use for "historyurl".