I have found reference documents for this topic at Cisco "Sample Configuration: IPSec Tunnel - Cisco Router to Checkpoint Firewall 4.1" and at Chekpoint " Check Point VPN-1 and Cisco IOS Gateway to Gateway IKE VPN using Pre-shared secrets".
I have also had similar problems with Checkpoint products. My interim solution has been to use multiple hardware profiles on our laptops. By configuring descriptive profile names - "Remote-Dialup Only" for modem access. - "Remote-Network support" for...