Try it via the JDM first.
When you configure the MLT, just select the LACP option.
If the JDM doesn't do it, you'll have to use the CLI and put in something like:
interface FastEthernet 1/1-2
lacp aggregation port 1/1-2 enable
lacp mode port 1/1-2 active
lacp key port 1/1-2 101