An easier way to add a screen may be to add one of these, instead of trying to mod the PSONE LCD screen:

With the Standard/Universal Model you can connect it directly to any A/V input.
So with this, instead of adding a screen, wiring the output to a set of A/V plugs you could add this, making room for memory cards(for those systems that use them) or more battery space for longer usage.
Here are the details for the MyVu:
Technical Specs:
Product Classification: Binocular Head Mounted Video Display
Battery: Rechargeable Lithium Polymer
Battery Operation Time: 4 Hours
Battery Charging: USB Mini Connection Cable, 5 Volts/300 mA
Charging Time: 2 Hour Fast Charge (USB A/C Adapter) - 4 Hour USB Charge
Mechanical Specs:
Headset Weight: 70 grams
Headset Temples: Foldable, with Spring Extension
Cable Clip: Moveable Cable Clip Included
Nosepiece: Three Sizes, Adjustable
Earphones: In-Ear, Ultimate Ears Earphones, Three Insert Sizes
Operating Temperature: 0 degrees Celsius - 40 degrees Celsius
Display:
Optical System: V1 SolidOptex®
Display Resolution: 320 x 240 (QVGA)
Color Depth: 24 bit Color
Aspect Ratio: 4:3
Field of View: 16.9 degrees Diagonal
Eye Relief: 25 mm
Display Technology: Transmissive LCD MicroDisplay
Nominal IPD Accomodation: 63.5 mm
Display Focal Distance: 1.5 meters
Electrical:
A/V Input Connector: 3.5 mm A/V Jack
Video Input: Composite Video, NTSC/PAL
Audio Input: Headphone Audio Input
Video Controls: Brightness, Contrast
Other:
Prescription Correction: Available Prescription Correction Clip-On Lens
I just thought of it recently after seeing these in a local Macy's Vending Machine

