Connect a portable USB modem (data card) with Samsung Galaxy S II
It's difficult to say with absolute certainty, but generally speaking that is not possible. Some devices can be patched and hacked to include support for this, but I am not aware of one for the Samsung Galaxy S II on any kernel. The flash drive, mouse and keyboard support is built-in to Android whereas USB network dongles need to be hacked on to it. I know it is possible on a number of Nvidia platfoms to connect Huawei USB dongles, but on the Samsung gear, I've never seen a way.

In short, that's not known to be possible on the Samsung Galaxy S II ICS.