GCAM customized policies

[rp9823]

I have 3 questions:

1. Is there any available guide on how to set up a customized policy on GCAM?
2. If i want to run a scenario with one of the "pre - defined" policies, e.g. carbon_tax_10_5, should I add the policy to the scenario components in the configuration_ref file or in the configuration_policy? because I noticed they're slightly different.
3. If I set a scenario by fixing the emission pathway and solving for carbon price, should I enable the target finder mode?
   Thanks