Change to the directory containing the code and run the following command:

cvs -d [path to CVSHOME] import -m [comment] [modulename] [vendortag] [releasetag]

this will import the entire directory and all subdirectories (including hidden files) into a new module in the repository.
Now you can checkout the sourcecode and begin working.
NOTE: The directory just added cannot be used to work in, since it is now a CVS directory yet.

Example:

cvs -d /mnt/data/CVSHOME import -m"Initial import from version 0.1" miav MyCompany main