[jQuery] [jQuery Validate]Validating for incremental form

[gMinuses]

I have the form:

<form>
    <div id="portion1">
        ... some inputs ...
    </div>
    <div id="portion2">
        ... some inputs ...
    </div>
    <div id="portion3">
        ... some inputs ...
    </div>
</form>

By default, only #portion1 is visible. If inputs inside it are all
valid, #portion2 will be visible and #portion1 will be hidden, and so
on.

The problem is that jQuery Validate will only validate the whole form,
so something like $('#portion1').validate().form() won't work.

So, is there a way to achieve this?
Thanks.