php - magento pay some part of order payment at checkout and rest after delivery -

php - magento pay some part of order payment at checkout and rest after delivery -

i want create / add together custom method user have pay percent of total order @ checkout 50% of order amount , rest amount have pay when order gets delivered how can that. observer need check ??

need phone call observer before checkout see http://www.silksoftware.com/magento-module-creator/

php magento