Integrate DineroMail (payment gateway) into wordpress

Hi!
I want to integrate a payment gateway that′s very popular in my country with a WordPress shopping cart plugin.
the plugin could be eShop, wp-ecommerce or whatever plugin you are familiar with.
The gateway is called DineroMail and they sent me a guide to do this.
In this guide they say that I should make that the “Pay Now” or “Checkout” button of the Shopping Cart get all the information charged in the Cart and send the information for each field to the following URL: https://checkout.dineromail.com/CheckOut
The example code for the button is:

<form action="https://checkout.dineromail.com/CheckOut" method="post" >
<!-- Sale settings -->
<input type="hidden" name="tool" value="cart" />
<input type="hidden" name="merchant" value="0001" />
<input type="hidden" name="seller_name" value="E-Commerce" />
<input type="hidden" name="languge" value="es" />
<input type="hidden" name="transaction_id" value="11122233" />
<input type="hidden" name="currency" value="ars" />
<input type="hidden" name="ok_url" value="https://www.ok.com" />
<input type="hidden" name="error_url" value="https://www.error.com" />
<input type="hidden" name="pending_url" value="www.pending.com" />
<input type="hidden" name="additional_fixed_charge" value="5" />
<input type="hidden" name="additional_fixed_charge_currency" value="ars" />
<input type="hidden" name="buyer_message" value="1" />
<input type="hidden" name="header_image" value="https://www.ecommerce/Logo.gif" />
<input type="hidden" name="header_width" value="1" />
<input type="hidden" name="change_quantity" value="1" />
<input type="hidden" name="display_shipping" value="1" />
<input type="hidden" name="display_additional_charge" value="1" />
<input type="hidden" name="expanded_step_ PM" value="0" />
<input type="hidden" name="expanded_step_ AD" value="0" />
<input type="hidden" name="expanded_step_ SC" value="0" />
<input type="hidden" name="expanded_sale_
<input type="hidden" name="item_weight_1" value="0400" />
<input type="hidden" name="shipping_currency_1" value="ars" />
<!-- Item 2 -->
<input type="hidden" name="item_name_2" value="MP3" />
<input type="hidden" name="item_code_2" value="021" />
<input type="hidden" name="item_quantity_2" value="1" />
<input type="hidden" name="item_ammount_2" value="8000" />
<input type="hidden" name="item_currency_2" value="ars" />
<input type="hidden" name="shipping_type_2" value="2" />
<input type="hidden" name="shipping_cost_1_2" value="1000" />
<input type="hidden" name="shipping_cost_2_2" value="500" />
<input type="hidden" name="shipping_currency_2" value="ars" />
<!-- Buyer info -->
<input type="hidden" name="buyer_name" value="Juan Carlos" />
<input type="hidden" name="buyer_lastname" value="Lopez" />
<input type="hidden" name="buyer_sex" value="m" />
<input type="hidden" name="buyer_nacionality" value="arg" />
<input type="hidden" name="buyer_document_type" value="dni" />
<input type="hidden" name="buyer_document_number" value="12345678" />
<input type="hidden" name="buyer_email" value="jclopez@buyer_email.com" />
<input type="hidden" name="buyer_phone" value="55555555" />
<input type="hidden" name="buyer_phone_extension" value="123" />
<input type="hidden" name="buyer_zip_code" value="1234" />
<input type="hidden" name="buyer_street" value="buyer_street" />
<input type="hidden" name="buyer_number" value="123" />
<input type="hidden" name="buyer_complement" value="buyer_complement" />
<input type="hidden" name="buyer_city" value="buyer_city" />
<input type="hidden" name="buyer_state" value="buyer_state" />
<input type="hidden" name="buyer_country" value="arg" />
<!-- Color Design -->
<input type="hidden" name="step_color" value="E7E7E7" />
<input type="hidden" name="hover_step_color" value="DFEFFF" />
<input type="hidden" name="links_color" value="0000D4" />
<input type="hidden" name="font_color" value="6699CC" />
<input type="hidden" name="border_color" value="F99800" />
<input type="hidden" name="button_color" value="6699CC" />
<!-- Additional data -->
<!-- Item 1 -->
<input type="hidden" name="additional_var_description_1" value="XXXXXXX" />
<input type="hidden" name="additional_var_value_1" value="XXXXXXX" />
<input type="hidden" name="additional_var_visible_1" value="1" />
<input type="hidden" name="additional_var_required_1" value="0" />
<!-- Item 2 -->
<input type="hidden" name="additional_var_description_2" value="XXXXXXX" />
<input type="hidden" name="additional_var_value_2" value="" />
<input type="hidden" name="additional_var_visible_2" value="1" />
<input type="hidden" name="additional_var_required_2" value="0" />
<input id="Submit" type="submit" value="button" />
</form>

What information should I put in “value” on the inpunt codes, where can I find this on the plugin?
Any orientation such as tutorials or what should I learn to do this ir welcome.

thanks!