I was looking to do the same thing and so I dug into the API and although it often doesn't explain what many things are it at least gives me some hints of what is possible.

Here I see in the API docs (Laravel 4.2) that you can pass an attributes array to the validator class. I just took a quick guess and the following did work:

$attributes = [
    'category_id' => 'Category ID',
    'regid' => 'Registration ID #'
];

$rules = [
    'category_id' => 'required|min:10|max:30|alpha_num',
    'regid' => 'required|digits:10'
];

$validator = Validator::make(Input::all(), $rules, [], $attributes);

You may notice I had no $messages so I simply passed an empty array so defaults were used, however I could have passed those as well.

I would imagine you could use Lang:get('field_name') to fill in your $attributes array values as well.

Please note, I was only making a guess and didn't actually look at the Validator class in more depth (and I am new to Laravel) so perhaps this is more of a hack than a solid solution.