Lick

The problem: I am trying to board a helicopter which is hovering low. Because it is moving, the option to board it on the mouse scroll list is constantly disappearing and then reappearing. This means selecting that option is a bit tricky and can cause me to unintentionally check my gear or draw my pistol. In the controls menu it is possible to assign keys to get out or eject from vehicles/aircraft. There is no such option for boarding. Is it possible to set something up? Many thanks.