Well, you can step through eval'd code, but you probably
won't see the source lines since the debugger gets access
to the source lines by reading from the file that Perl read
Breaking on Module::function should work provided that the
module has already been required. Of course, there are
lots of fun things that modules can do that make this break.
Autoloading is the most common. For example, much of CGI
is generated when you need it, which makes debugging that
code nearly impossible (because the code for most of the
subroutines was eval'd).
(but my friends call me "Tye")