Is it that big? Can't you just slurp it in into a scalar, as chromatic suggested, and save yourself some hassle?

Here are some alternatives:

Use external plain file

{
   local @ARGV = '/home/michaelg/helpfile';
   print <>;
}
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Use external DBM file (with tie/dbmopen). This way you can easily handle more messages.

my %msgs;
dbmopen %msgs, '/home/michaelg/dbmhelp', 0600;

print $msgs{mainhelp};     
# [...]
print $msgs{braindead_help};
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Here-docs also come handy

print <<'FINIS';
I gave foo bars to the foo fighters , and of course Dave 
well never mind ,
[...]
FINIS
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