You can use the -I command line argument when invoking perl. For example, let's say that you have a script called my_test.pl in the current working directory which uses your version of the Foo::Bar module. Also, your version of the Foo::Bar module is in a subdir (in the current working directory) called lib. So, your file structure should look like this:

./my_test.pl
./lib/Foo/Bar.pm
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Use the following to run your script using your version of Foo::Bar

perl -I lib/ my_test.pl
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This will work for simple pure perl modules, but you may have issues if your module is more complicated (e.g. uses XS, File::ShareDir, etc.).