It's not clear to me what the problem is, since I can't run the script. But do you mean to use decode (from Encode.pm), instead of encode?

UPDATE: I looked at textlabel in PDF::API2::Content, and if you trace it back it goes to:

sub add 
{
    my $self=shift @_;
    if(scalar @_>0) 
    {
        $self->{' stream'}.=encode("iso-8859-1",($self->{' stream'}=~m
+|\s$|o?'':' ').join(' ',@_).' ');
    }
    $self;
}
[download]

which is calling encode iso-8859-1 on whatever gets passed in. Oops.