Emacs also has a "ESC x comment-region" command (which I have bound to a key, myself). Select the block of multi-line text, do a comment-region, and in cperl-mode, "# " will magically appear in front of every line. If you do a "C-u" prefix first, you can use the same command to remove the commenting.

Alternately, it's not at all difficult to write keystroke macros that do things like "insert a '#' in front of this line and then move down one line", which you can loop to comment a series of lines.

The default keystrokes for that (Off the top of my head, and untested):

Defining the macro:

  C-x ( 
  C-a 
  # 
  C-n 
  C-x )
[download]

Running it once:

  C-x e
[download]

Running it 10 times:

  C-u 10 C-x e
[download]

My personal preference: don't use one of the workarounds. Everyone understands "#" commented lines, but many will find your workaround confusing. Optimize for readability, not for ease of typing.

But if you do use a workaround, my preference would be for abusing pod ('=for comment/=cut'), which is endorsed by Damien Conway in "Perl Best Practices".