binding a collection to a setter method of a domain class in grails

Question

I have a domain object with a setter method that takes in a map of id, value pairs. This is not just a plain association, and this setter method has some login in it. For example:

class DomainObj{
  def setTheMap(map){
    //do stuff with the map
  }
}

I have a form where the user can type in a value for each id. My goal is that when the user posts the data back and I set domainObj.properties = params, the method setTheMap will be called passing in a hash of the form:

[id1: 'string1', id2: 'string2', id3: 'string3']

However, I can't figure out how to format the text-fields in the view to accomplish this. Currently I have to following which does not work:

<g:textField name="theMap.id1" value="string1" />
<g:textField name="theMap.id2" value="string2" />
<g:textField name="theMap.id3" value="string3" />

Is there an easy way to accomplish this? I was reading that as of grails 1.1 you can do this sort of thing for maps of associations, but I can't find any info about doing this for arbitrary setter methods.