m0n0wall to Cisco ASA 5505 IPSec VPN

I am trying to setup a VPN from a site with a 1.3 m0n0wall on a Soekris 4801 to a site with a Cisco ASA 5505. I have no control over the Cisco.

I have been supplied the following parameters by the other end:
Remote Peer IP: 66.<snip>
Remote Network: 192.<snip>/24 (255.255.255.0)
Your Local Network: 10.1.2.<snip>/32 (255.255.255.255)

Phase 1
Negotiation Mode: Main
Authentication: Pre-Shared
Encryption: 3DES
Hash: SHA
DH: 1
Lifetime: 86400 sec
Pre-shared Key: <snip>

Phase2
ESP encryption: 3DES
ESP authentication: SHA
Lifetime: 28800
PFS: Disabled

The instructions from other end state that I  will need to make an IPSec ACL from 10.1.2.<snip>/32 to remote network 192.<snip>/24 and I will need to NAT interesting traffic to 10.1.2.<snip>/32 (255.255.255.255).

My problem is that 10.1.2.<snip>/32 does not exist on my network. Our local subnet is 192.168.100.0/24. It sounds like I need to make traffic coming from our server (192.168.100.x) destined for their subnet (192.something not 168.100.0/24) look like it is coming from 10.1.2.<snip>/32. I would guess that Advanced Outbound NAT is what is needed. But I cannot get the tunnel up with a local endpoint of 10.1.2.<snip>/32

I am quite sure that if I had an ASA I could do this (if I knew what I was doing on an ASA). Can this be done on a m0n0wall? If not m0n0wall can pfsense do this?

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James W. McKeand