apt-get install ifenslave

make sure the real NICs kernel modules are loaded automatically

modprobe --list | grep -i bonding

edit /etc/network/interfaces to look like this:

auto bond0
iface bond0 inet static
address 192.168.1.59
netmask 255.255.255.0
gateway 192.168.1.1
up /sbin/ifenslave bond0 eth0 eth1
down /sbin/ifenslave -d bond0 eth0 eth1
broadcast 192.168.1.255

make sure to remove ALL of the lines refering to old eth0 or eth1 settings.

add the following lines to your /etc/modprobe.d/arch/i386:

alias bond0 bonding
options bonding mode=1 miimon=100 downdelay=200 updelay=200