4-Port 8Gb FC module to 2-Port 10Gb FCoE Module

I am looking for a definite answer on the following problem I'm having.

(Assume I'm doing this to both SPs, even though I mention one card.)

I have a VNX5400, and I have a 4-Port 8Gb FC IO Module installed.  This was committed to the system, as it was installed using USM to manage the install.  No hosts or cables were ever used on these ports.

We would like to Upgrade this IO module to a 2-Port 10 Gb FCoE IO Module.  Is this possible?  Do I need to get 2 IO Modules so that I can upgrade the 4 port FC card to 2 separate 2-Port 10 Gb FCoE cards? 

I understand that removing or downgrading a IO Module in the SP normally requires nuking the configuration and data on the box.  Since this is a production frame with production data, I can not consider this an option.

So, given these parameters, is this upgrade possible?  Would I be able to upgrade the card, by adding 2 2-port cards to keep the same number of ports? Am I just out of luck and need to install the module in the last slot and leave this FC card unused?