Therefore '.' is not in @INC. I used use lib dirname($0);

Note that these are not equivalent. The former puts the current working directory into @INC, which IMHO is not as portable as an absolute pathname, and the latter puts the path where the script is located (assuming $0 was resolved correctly!) into @INC, the two are not always the same! The better version of the latter is use FindBin; use lib $FindBin::Bin;, which I would recommend.

I am having some troubles using the Perl libraries in the directory ccc. Is it because of the '\'?

Since you didn't give us exact error messages or an SSCCE, we don't know and would have to guess.