Add other merchant service beside PayPal

I want to add additional merchant service for my cart. I want to use it because I need it so that Malaysian customers can pay using internet banking if they don't have credit card. When I ask them whether they support zen-cart or not, they said 'Yes, but we don’t have ready plugin for zen cart. You need to integrate your self.' How to set it up? This is their website "https://webcash.com.my/".

Second Q is, is it possible for me to do like this?
Since both PayPal and WebCash accept credit card but the fee is different.
--> For credit card customers only <--
Condition 1
If the customers is Malaysian, and the total payment is lower than RMxxx.xx , then he will be used WebCash platform otherwise, he will use PayPal platform.
Condition 2
If the customers is Non-Malaysian, and the total payment is lower than RMxxxx.xx , then he will be used WebCash platform otherwise, he will use PayPal platform.

Thanks!