Use $OPENSSL_X509_CERT_FILE to get the CA certificates.

diff -ru -x '*~' LWP-Protocol-https-6.02-orig/lib/LWP/Protocol/https.pm LWP-Protocol-https-6.02/lib/LWP/Protocol/https.pm
--- LWP-Protocol-https-6.02-orig/lib/LWP/Protocol/https.pm	2011-03-27 13:54:01.000000000 +0200
+++ LWP-Protocol-https-6.02/lib/LWP/Protocol/https.pm	2011-10-07 13:23:41.398628375 +0200
@@ -21,6 +21,11 @@
     }
     if ($ssl_opts{SSL_verify_mode}) {
 	unless (exists $ssl_opts{SSL_ca_file} || exists $ssl_opts{SSL_ca_path}) {
+            if (defined $ENV{'OPENSSL_X509_CERT_FILE'}) {
+                $ssl_opts{SSL_ca_file} = $ENV{'OPENSSL_X509_CERT_FILE'};
+            }
+        }
+	unless (exists $ssl_opts{SSL_ca_file} || exists $ssl_opts{SSL_ca_path}) {
 	    eval {
 		require Mozilla::CA;
 	    };