Looking in the docs they only offer examples with data attributes, I need to write a different js file for a form and do something like:
$('#myform').parsley(options);
I want to know the available methods in options, and apply validators to inputs and then print custom messages.
It is possible?
Yes, just use the camel case equivalent. See also the defaults
Some javascript methods are in the documentation, others you have to look in the source.
For example, (see this on how to add the corresponding validator):