First read the README file. If it does not help: perl Makefile.PL; make test; make install
should do the trick. But the best way to do it would be by using the CPAN module: perl -MCPAN -e shell. There is a help command in it - so you should not be lost there. The command install Sys::Alarm would download the module, compile it (if it is needed) and install it for you.