I always thought it would be cool to have some kind of voting with $$ system to get certain performers and decide on some scenes/positions but the market of customers may not exist
Like @VRHotwife said, going direct and offering enough cash will be the best shot
Otherwise you can go to the VR livecam section and get whatever you want for enough tokens. I dream of the day SLR can add a private show recording feature that Stripchat has