Game Input MultipleXer

I'm playing BO3 and Division with a keyboard and mouse using a DIY adapter , my only question is with the special abilities you need to press l2 and r2 at the same time. I have these bound to my mouse but sometimes its hit and miss. Is there a way to keep them separate on the mouse so I can still use them and map a single button on the keyboard to press l2 and r2 at the same time?

Thank you

I'm using the latest software on Windows 10 64Bit

Use gimx-config to do advanced bindings.