I can talk you through removing the headliner, hit me up via private message as this would be much easier over the phone.
As stated, the generic way is to remove all the trim ( if only weather stripping over the windows, then pull it down ) if plastic or metal trim, remove it and set it in the floor of the seat it came out of. The front pillars going along the sides of the windshield, the center pillar covers ( where the driver's and passenger seat belts r mounted ) need to be loosened at minimum, removing them makes the job easier, then the rear trim ( rear side window area ) remove that or loosen it.
All lights removed, visors removed, at this point you check for velcro holding the board up....the very front by the rear view, the very rear ( underneath the luggage rack area ) and the most pita part.....make sure any factory wiring 'hotglued' to the board is removed carefully so as not to break any connections. Take your time with all electrical connections as they are small and weak, treat them like glass.
Once the board is loose and suspending on the loosened trim, you move the board all the way ( right or left, doesn't matter ) one way and then pull it out of the trim on the opposite end. Then, as stated, straight out the back. Car headliners come out the passenger door w/ the seat laid back.
If you need any further assistance, send me a message here...if i'm home, i'll talk you thru whatever you need.