Is it possible to add quantity on the product page

-- HikaShop version -- : 2.3.2
-- Joomla version -- : 3.3.3
-- PHP version -- : 5.4.27
-- Browser(s) name and version -- : all

Is it possible to add quantity on the product page.

I have a product that needs to be ordered in the quantity 6,12,18,24 etc.... and another that needs to be ordered in quantity 12,24,36,48 etc... because thats how the boxes are packed.

Is that possible to do and if yes how do i do it?

if i do that it starts at 6 but then it goes to 7 if i press + i want it to go to 12 so that it puts 6 each time like 6 - 12- 18 -24 etc.
How do i do that?

Like this

Purchase Quantity Steps 6 so it goes 6 - 12 - 18 - 24 etc. and for another product 12 - 24 - 36 - 48 etc.
Minimum Purchase Quantity 6
Maximum Purchase Quantity 9999

Can that be done easily?

Is it not possible to do it with the + and - , it looks better than a long dropdown