There's a The Effective Perler article on custom tracing entitled Trace your Perl programs that you might find useful, particularly the last example.

To summarize...

• Under the -d switch, perl calls &DB::DB before each statement
• You can write your own tracer (e.g., Devel::Foo) to define your own &DB::DB that excludes third-party modules, and run it via -d:Foo
.