If you are referring to pre-paid cards/topups such as Ukash or Paysafe cards you can already do this, these methods involve going into a shop and topping up/purchasing a voucher/card and then typing in the code using our PaymentWall options.
On the PaymentWall donation options just look for the icon which looks like this:

and it will allow you to find out more information about which pre-paid cards are supported locally to you and from there you should be able to do so. This is also where the cards should be used if you ever purchase them.
We also offer a range of different donation methods as explained in more detail on the
Donation page.
But as always please get permission from whoever is paying for these things, we don't want to have to ban players who reverse payments because they didn't get permission to use money from their parents, etc.