The binary-packet I just downloaded unfortunately doesn't have
the vde_pcapplug so I can't check if it works like that but you
can try something like this as a minimal setup (everything in an
extra console till it works afterwards all modules offer daemonization):

vde_switch -s /var/run/vde_sock
slirpplug -s /var/run/vde_sock -D
vde_pcapplug -s /var/run/vde_sock wlan0

We don't care for gprs0 as this is gonna be done by the
IP-stack.
I found a couple of hours time in the train so I'm quite far
with stripping down qemu to what we need here. So I will
try to go for that to have everything in a single binary and
to avoid the socket-communication.