Netgear DG834GB how to restrict bandwidth?

I am generally very satisfied with my
NETGEAR DG834GB ADSL Modem / Router -
(hardware revision v3)
I use it on an 16 mbits / 1 mbits ADSL line
and i have 2 computers connected to it via
Ethernet,
and one more via wLAN.
Port-forwarding is configured properly and
all works fine.

Now i want to share the internet with my
neighbour and we have already
tested it and everything works fine aswell.

The only question is:
it seems that the router software does not
allow
the restriction of used bandwidth.
I would however like to do this as i
generally require "half" of the
16 mbits downstream and would like to
"restrict"
my neighbour to 8 mbits up (and 256 kbits
down).

Is there any bypassing way around this
problem?
any ideas?

many thanks in advance

Roland Schweiger