Its a little difficult to be sure as you haven't wrapped the text of the error msg in code tags and so it looks as though some extraneous spaces have been included but...

It looks like you have the path to the relevant subdirectory prefixed with './' thereby making this path a relative rather than an absolute path.

./usr/local/lib/perl5/site_perl/5.8.0/PA-RISC2.0/MQSeries/
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If this is true and not just an effect of the formatting, unless your script is being run from root, the values in @INC will not allow the module Queue.pm to be found, which is exactly the error message you are receiving.

This is how I have parsed the error message you posted.

Can't locate MQSeries/Queue.pm in @INC (@INC contains: 
/usr/local/lib/perl5/5.8.0/PA-RISC2.0 
/usr/local/lib/perl5/5.8.0 
/usr/local/lib/perl5/site_perl/5.8.0/PA-RISC2.0 
/usr/local/lib/perl5/site_perl/5.8.0 
/usr/local/lib/perl5/site_perl 
./usr/local/lib/perl5/site_perl/5.8.0/PA-RISC2.0/MQSeries/
) at ./mqlogin.pl line 19.
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My apologies if I have mis-parsed it and this is a red-herring.