location of 'com.apple.versioner.perl'

A script using Mac::Processes failed on OS 10.6.3 because of a 64/32  
bit issue. Following the recommendations in 'man perl' I ran

defaults write com.apple.versioner.perl Prefer-32-bit -bool yes

which fixed the problem.

However for the life of me I cannot find the file  
'com.apple.versioner.perl.plist' on that machine. It is not in / 
Library/Preferences. What am I missing?

Secondly in a '.pkg' distribution for the script how should one manage  
the possibility the installation might be on either a 32 bit or 64 bit  
system? Is there any disadvantage in running that 'defaults' line  
(above) irrespective of the OS (and/or) Perl versions?

Suggestions would be most gratefully received.

Alan Fry