Is it possible to toggle the Modify Weapon Attachment key instead of holding it?

Is it possible to toggle the Modify Weapon Attachment key (Plus Menu) instead of holding it?

I'm on PC and it's T. I find it very awkward that this button must be held in order to change weapon attachments.  It is possible to toggle it like click to open and click to close instead of holding it all the time? 

Thank you

BTW I just bought the game and it seems that the game is relatively dead... 

[Edit: Formatting amended for one paragraph - ElliotLH]