Hi,
It makes sens but I don't know how it could be possible.
You can create a button which will redirect wherever you want to but, HikaShop is managing the cart and the orders. You have to send these data to the other system.
Everything is possible, but it requires some development.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.