I'd suggest that you use LACP in order to bond the two devices.
So before we begin, you should know that I have two assumptions before you start.
You are familiar *and* COMFORTABLE with opening a terminal window and mucking around with the innards of OS X.
You are at least *somewhat* comfortable with ifconfig
and know how to identify the two network devices that you want to play with.
Outside of those assumptions, the GUI within OS X will not, otherwise, allow you to bond the airport connection with the wired connection until you confux0r it manually.
Now, we can get under way.....
What you'll want to do first is open a terminal window.
Type the following BOLD
commands (without the # signs
# sudo -s
(you're asked for your password, so enter it already... time is wasting!)
# ifconfig -a
(search for the open ethernet devices that you want to use- you originally suggested en0+en1, so... use those if you are *certain* that they are what you want to play with.)
# ifconfig lagg0 create
# ifconfig lagg0 up laggproto lacp laggport en0 laggport en1
interface allows aggregation of multiple network interfaces as one virtual interface for the purpose of providing fault-tolerance and high-speed links.)
View the interface status by running:
# ifconfig lagg0
The output *should* look something like this:
# lagg0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
# ether 00:05:5d:71:8d:b8 <- Note that there will be only ONE ethernet address shown
# media: Ethernet autoselect
# status: active
# laggproto lacp
# laggport: en1 flags=1c<ACTIVE,COLLECTING,DISTRIBUTING>
# laggport: en0 flags=1c<ACTIVE,COLLECTING,DISTRIBUTING>
(Ports marked as ACTIVE are part of the active aggregation group that has been negotiated with the remote switch and traffic will be transmitted and received.)
From there, you can now go in to the System Preferences > Network Settings and view the lagg0 connection device and configure it with that damned GUI that didn't cost you anything at all.
You'll want to also arrange the order of the network devices so that lagg0 appears at the top of the list, and set it up to work with either DHCP or manually- as your networking needs and desires dictate.
Finally: I do know that attempting to *create* a LACP "virtual device" with an airport and an ethernet device can not be done via the default Network settings as Apple decided to prevent that from happening. This was probably because in most instances, wired ethernet will always be a lot faster than wireless. However, once it has been created, you can manage it like any other network device that OS X can see. Since both of those devices are already recognized by OS X, you shouldn't have any issues with them...
Let me know if you run in to problems, as I may or may not be able to help out. However, that *should* work, as I've done it before with 10.5x as well as with a variety of BSD OSes.