Ok, I can save params in both shipment and payment plugin but when i try to checkout I have this problem with shipment:
500 - JDatabaseMySQL::query: 1054 - Unknown column 'virtuemart_shipmentmethod_id' in 'field list' SQL=INSERT INTO `dl5ar_virtuemart_shipment_plg_weight_countries` (`id`,`virtuemart_order_id`,`order_number`,`virtuemart_shipmentmethod_id`,`shipment_name`,`order_weight`,`shipment_weight_unit`,`shipment_cost`,`shipment_package_fee`,`tax_id`,`created_on`,`created_by`,`modified_on`,`modified_by`) VALUES ('0','79','ed4d3ec2','0','Bartolini','0','KG','0','5','0','2011-12-04 21:03:55','0','2011-12-04 21:03:55','0')
I tried to adapt the requested fields in weight_countries.php to fit your query and adding the last 4 columns (`created_on`,`created_by`,`modified_on`,`modified_by`) to the table.
After that i got a fatal error on /plugins/vmpayment/paypal/paypal.php on line 108
$order_number = $order->getOrderNumber($cart->virtuemart_order_id); commeting this line I finally can see the paypal site.
How this can help you.