$SIG{ALRM} = sub { die "timed out" };

eval {
   alarm(60); # give it 60 seconds
   $response = $useragent->simple_request($request,\&callback,2048);
   alarm(0);
};

# now look for "timed out" in $@

if ($@ =~ /timed out/) {
   # do something
}

##</code><code>##

undef $useragent if $@ =~ /timed out/;