How to accept underscore(_) as JSONP callback (/mywebsite.......com/myapi...../?_=callbackfunctionname&)?

Hi,

I have to make BOTH underscore( _ ) and callback acceptable for my WebAPI.

I am using JSONP

eg: 

/mywebsite.......com/myapi...../?_=callbackfunctionname&

and

https://mywebsite.......com/myapi...../?callback=callbackfunctionname&

Can anyone please tell me what changes I should make to get them working?

Thanks,