Pairing of copper and fiber interfaces is not supported.
We have not tested this configuration and do not know what issues might develop from that combination.
Here is the list of supported inline interface pairs:
http://www.cisco.com/univercd/cc/td/doc/product/iaabu/csids/csids12/cliguide/cliinter.htm#wp1057307
Alternatives:
1) Purchase a second SX interface from Cisco so you can pair the 2 SX interfaces.
2) Use InLine Vlan Pairs which pairs 2 vlans on a single interface instead of using 2 interfaces. You can then create inline vlan pairs on the SX card, and can even created inline vlan pairs on the TX interface ofthe motherboard at the same time.
Marco