I can't change OS right now to check, but do you remember if it's possibile to decide where the point_tesla fires its sparks? maybe with info_targets?

I don't think it's possible to get it to hit a specific target because it fires randomly. You can change the radius and entity than creates the sparks though.

There is no way I know to get this working. You would have to use env_beam or env_laser for this.