Bonding with cable modem 802.3ad LACP

Hi, I am trying to figure out how to do link aggregation in openwrt. Please help if you have a successful implementation method.
What I found so far in package:
I also found luci proto bonding in some Asian mods package.

It seems doable but I cannot find any detail on how to setup or implement the 802.3ad link aggregation.
I also sees DDwrt can do 802.3ad link aggregation but cannot find any instruction for Openwrt.
The reason for me to do bonding is my cable modem (arris sb8200) support link aggregation with two ports and I see people use LACP to reach 1.2G speed on a 1G Cox gigablast package (well they use other router distro.). I have x86 machine with quad port nic so hardware wise should not be an issue. Yeah I know LACP could be done easily with a managed switch. I also understand other router distro can do the job but I like Openwrt's active development and Arm cpu support so I am planing to spend more time on Openwrt.
Thanks in advance.