allow external network to access internal and vica-versa

[picnmix]

Hi all,
I have this setup which is giving me a head-ache.

br office 192.168.17.0/24
|
|
Cisco pix 192.168.17.254/24
|
| vpn tunnel between the pixes
|
Cisco pix 10.0.0.254/24
|
|
External nic of isa 2004 10.0.0.1/24
|
Internal nic of isa 2004 192.168.16.2/24
|
|
|
Internal clients 192.168.16.0/24

I want to be able to ping/rpd from the Internal clients to the Br office clients.

What do I setup on the ISA to let the internal talk to the subnet 192.168.17.0/24?????