I think that furnishing the stakeholders with adequate information and then consulting them is the best way to get buy in for initiative like this.

I think that it's better that you create a simulation on how much it will cost the company if employees with salary above RM 2,000 is paid overtime. You can simulate few scenarios e.g. where the employees is paid according to EA rates, and also where the employees is paid a flat rate. After presenting the simulations result to the top management and they're agreeable to pay OT, make a survey between the subjected employees whether they prefer the approved OT method or replacement leave / time out system.