After looking some more into it, figured out the following:
- /etc/ppp/ip-* aren't called because IPSec connections not managed by pppd. They are managed by racoon
- providing script configuration parameters for phase1_up and phase1_down would be perfect option... but configuration for racoon created on the fly and I couldn't find a way to hook into it
With above options exhausted, I turned to concept laid out by Onne Gorter here: http://tech.inhelsinki.nl/locationchanger/. Script gets called when Network configuration changes, analyses whether VPN is up or down and acts accordingly. It is not exactly what I wanted since it called on every network configuration change but close enough.
Any other ideas, please share.