Set up Passive/Active Health Monitoring

This doesn't actually relate to iRules. The inband monitor is simply a Health Monitor. I'd agree there's little detailed information, like here for instance: http://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/ltm-concepts-11-4-0/16.html.

Also note this issue if your device has a PVA: http://support.f5.com/kb/en-us/solutions/public/10000/600/sol10689.html.

If you really want to use the inband monitor, I'd suggest setting it up on a test system (or Pool or whatever) and seeing how it works in your environment.