For the non squeamish go to http://europe.nokia.com/A4425308 otherwise read on:
What I'll be doing in this guide is essentially hooking a naked wire around the contact from the gps antenna and wrapping that wire around the phone in order to form a crude improvement upon the existing built in antenna.
What you will need:
1x Nokia N95 (any variety will do)
1x piece of wire
You will not need a screwdriver as we won't be undoing any screws. That said I'm pretty sure that getting the back off your phone will invalidate your guarantee.
Please be advised that the use of this guide is your entire responsibility. I hereby disclaim all responsibility and will not be made liable for any damages of any kind.
Step 1: A Simple Brief
With the phone facing you and display pushed up to reveal the keyboard you'll find the antenna stuck to the plastic housing around the MiniUSB and power connector.
Just to give you an idea of the location I have used an image of the N95 motherboard devoid of all other components. The chip itself is located on the back of the motherboard behind the keypad.
The antenna is attached via a sort of metal prong to the motherboard in a similar way a speaker or microphone would be attached.
Step 2: Remove the Cover
Remove the battery and SIM then get the plastic backing off.
Working from the right side (with the camera button) prise off the cover. It is held on by sticky pads so it should come off quite easily.
Step 3: Remove the Keyboard
This then comes away to reveal the keypresses themselves.
Step 4: Fit the Wire As an Extended Antenna
Form a hook at one end and use the hook to hook under the GPS antenna contact.
Pull this lightly such that the wire is under tension then wrap it round the plastic bottom end of the phone.
Take care to ensure that the wire touches no other metal component including the screws.
Earthing the antenna is IMHO a bad this as you'll be exposing the GPS chip and quite possibly other sensitive circuits directly to any static shock that the phone may get as part of it's daily life.
Step 5: Put Back Together
Put back the plastic cover starting from the headphone socket on the left. Click it back into place.
Insert your SIM and battery.
Step 6: Go Outside and Navigate
In my case I was able to lock on outside the Lyon PART DIEU train station even with the gps assistance disabled. Before this was impossible.
Let me and others know how you get on....