I need to perform some stuff with an array of primary keys.

I'd like to do something like:

$ids = array('my keys');

$table->find($ids)->from($this, 'a_field')->limitPage(2, 10);

Is this possible?

Yes this is possible.
What you are talking about is a composite key.

In order to facilitate this you just provide it as an array.

So:
This is what you suggested in your own post. Should have tried it