You could redirect STDERR for the time you make calls into that module.

package Foo;

sub foo { warn "blorf!" }
1;
[download]

#!/usr/bin/perl

use Foo;

use strict;
use warnings;

sub call (&);

call {
    Foo::foo();
};

if ($@) {
    warn "foo reported: '$@'\n";
}

## subs
#

sub call (&) {
    my $coderef = shift;
    my $message;
    open my $fh , '>&', \*STDERR;
    close STDERR;
    open  STDERR, '>',  \$message;
    $coderef->();
    open STDERR, ">&",  $fh;
    $@ = $message;
}
__END__
foo reported: 'blorf! at Foo.pm line 3.
'
[download]

That way all you have to do is wrap the places where you call into Sybase::CTlib into a block and dispatch that to the call() function.