prioritze ipsec VPN traffic over all other traffic

Hi guys,
I am trying to figure out how to prioritize VPN traffic.
I have a site to site ipsec vpn working.

At the main site I have a 20 meg link and at the branch site I have an adsl (8 meg down, 600k up).

What I would like to do is is have the vpn traffic have #1 priority over all the rest of the traffic. I dont want regular internet traffic to swamp the vpn traffic.
I want the vpn traffic to use 500k up max and the regular internet traffic to use as much as 500k up when there is no vpn traffic.

Any ideas as to how to do this?

See my signature for one approach to get you started.