I found the resolution. A couple notes for others: It appears that since I was accessing the service through an https endpoint, I needed to specify the firewall proxy protocol as https. From what I had read previously, I had through that specifying http would cover it. Guess not, perhaps I misunderstood. For one of the scripts, I was using a stubmaker.pl-generated pm which wrapped the various actions. As such, it was proving difficult to get access to the underlying http/https calls from within my script. I edited the pm _call() sub:

sub _call {
    my ($self, $method) = (shift, shift);
    my $name = UNIVERSAL::isa($method => 'SOAP::Data') ? $method->name
+ : $method;
    my %method = %{$methods{$name}};
    # added the following line so that we can utilize a proxy to get o
+ut through
    #        the firewall    
    $self->proxy($method{endpoint}, proxy => ['https' => 'http://proxy
+.mycompany.com']);    
    $self->proxy($method{endpoint} || Carp::croak "No server address (
+proxy) specified")
        unless $self->proxy;
    my @templates = @{$method{parameters}};
...
[download]

perhaps that was a bit less-than-elegant, but I was under the gun and can use my learnings to build on in the future Thanks!