the module currency exchange rate for webAsyst shop-script 307

Need to write a module of exchange rates for webAsyst shop-script 307:

Technical Task

Need the following functions were implemented:

1) assign each product provider and replace it with another (displayed only in admin panel)

2) the Price of the item in the admin should prizhivutsya in dollars or euros, and the site displayed in local currency.

3) the Ability to add or remove suppliers through the admin panel

4) the Ability to assign a currency to each supplier of its value.

Ie the goods presented on the website are purchased from different vendors with different currency exchange rates and the calculation may behave either in dollars or in euros.

For that would not change with every change in the exchange rate all prices on the website, we need such a module. Where I put down what course from each supplier.