Split DNS problem with Easy VPN

Hi all,

I was wandering if anybody ever tried this:

I am trying to connect a Cisco 871 router to a VPN3000
concentrator through Easy VPN using the router in
client mode and the VPN3000 as the Easy VPN server.

To allow more granularity, I want to use a virtual
interface associated with the Easy VPN tunnel.
According to the doc, I configure a virtual template
interface, which is cloned when the tunnel is
established to create a virtual access interface.

I can see the tunnel is established, i can ping and
connect to all machines behind the vpn3000, but all
DNS request are sent in clear out of the tunnel
instead of going through the tunnel to the corporate
DNS server.
I guess this is due to the split DNS feature
introduced in the IOS version I am using in the 871
router(12.4(9)T1). 
I really don't know how make the router send the DNS
request through the tunnel instead of sending them in
clear outside. 
Does somebody know?

Many thanks,

Rudi