Judging from comments here on perlmonks and my own experience there are no problems with using more than one version of perl concurrently. You could install perl10 in /usr/local, change the name of the executable to perl5.10, add /usr/local/bin to (the end of) your PATH environment variable and /usr/local/lib/perl5 to your PERL5LIB env variable. Any script you want to use with perl5.10 now only needs a short edit of its shebang line and you're done