I have to ask - considering what's required here, is it really worth your while getting an ethernet adaptor working on a laptop? I assume it has a wifi adaptor?
uhub(4) seems to detail some supported USB ethernet devices:
Code:
Wired network interfaces
aue(4) ADMtek AN986/ADM8511 Pegasus family 10/100 USB Ethernet
device
axe(4) ASIX Electronics AX88172/AX88178/AX88772 10/100/Gigabit
USB Ethernet device
axen(4) ASIX Electronics AX88179 10/100/Gigabit USB Ethernet
device
cdce(4) USB Communication Device Class Ethernet device
cue(4) CATC USB-EL1201A USB Ethernet device
kue(4) Kawasaki LSI KL5KUSB101B USB Ethernet device
mos(4) MosChip MCS7730/7830/7832 10/100 USB Ethernet device
smsc(4) SMSC LAN95xx 10/100 USB Ethernet device
udav(4) Davicom DM9601 10/100 USB Ethernet device
ure(4) RealTek RTL8152/RTL8153 10/100/Gigabit USB Ethernet
device
url(4) Realtek RTL8150L 10/100 USB Ethernet device
urndis(4) USB Remote NDIS Ethernet device
It might be worth looking into at least.