use lib

[B. Fongo]

Is it recommendable to use the pragma "use lib " when installing a
program on a server shared by many users?  
Assuming my IPS did not install certain CPAN modules which my needs, and
I decide to install them in my www directory. 
In such a scenario, putting "use lib" on my scripts will add my module
directory to @INC - which in fact isn't desired.
 
How can I avoid this situation?
Babs