How do you mark a Lead converted on record.js ?

Hello there !

What i want :

On Pro 7.5.2

For a client, when a user clicks on a custom button in a Leads' record, it calls an external API.
So, basically, i want that, if the api call is successful and we don't get any errors, i want to disable  editing on the Leads' record, and i want to mark it as "converted". (aka, get the convert button to turn green, and save the fact that the lead has been converted into the databases)


What i did :
I've managed to do this with the 
app.api.call('GET', app.api.buildURL('myCustomEndPoint/myCustomMethod/'+this.model.get('id')), null, { 
    success: function(date) {
        console.debug("Success!");
        var acls = app.user.getAcls();
        acls.Leads.edit = 'no'; 
        app.user.set("acls", acls);
        self.model.set('converted','1');
        /*$('[name="edit_button"]').hide(); */
    },
    error:function(error){
        console.debug(error);
    }
});


Where i am stuck :

For the "disable edit" part,  i tried to change the ACL on it -as you can see, but it does not seem to work. Do you have any idea on this?
But, well, this is not the most important question i have (really, because i can hide the "edit" button if i want to).

The most important question here is :

- How to mark the lead as Converted ? Aka : Being on record.js, how can i fill the database column "converted" with 1, and render the green button saying "Converted"

As you can see, i've tried with

this.model.set('converted','1');

but in the Firebug Console, it says that "this" is undefined, so i tried with declaring self = this before the api call. But it does not work either.


I would like it to change from 0 to 1 and to be saved in databases...

Thanks a lot for the ideas and the tips !