Jolokia plugin and custom_vars

Is there option to somehow set custom_vars for just one instance and not for the other, or to put it another way is there a option to set custom_vars per instance?
Currently all instances get queried for all defined custom_vars which ist not needed.
Before jolokia_generic became official part of check_mk there was “vars” property for instance and you could define custom mbeans per instance there.

Another question.
Sample jolokia.cfg says:

# Custom MBeans can be defined like this:
# (MBean, path/within/mbean, title, [], False, value_type)
#custom_vars = [
#('', 'FooBar/baz', 'Foo', [], False, 'string'),
# Supported Value types: 'string', 'number' and 'rate'

What does fourth([]) and fifth(False) property stands for? I could not find any info on this.