To quote Kernighan and Ritchie,
"The only way to learn a new programming language is by writing programs in it."
While going through
Learning Perl is important, there are a couple other standard documents he needs to read. Have him go through
perlref and
perltoot. But, it is probably more important to get programming quickly. Think of some mundane task that needs automating, and have him
design and implement an object oriented solution. This should give him the background in Perl to take over quickly.