Well, as everybody else seems not too keen to actually help....
You can edit the camera positions in GP3 Edit...
Set the following...
X = 0
Y = -255
Z = 165
Direction = 0
Pitch = -10
Roll = 0
That should get you somewhere near close to what you want, then you can fine tune the settings to your own requirements.
Just a note to explain the above, although this maybe slightly inaccurate, but it should help to a degree:
X is the camera position in relation to the centre of the car from left to right. Imagine sitting in the cockpit, a negative number will move the position to the left while a positive number will move to the right. Naturally 0 is in the centre.
Y is the camera position from the front of the car. 0 will be level with the very front and any negative number will move the camera further towards the back of the car. So the setting -255 is approximately level with the rear of the cockpit.
Z reffers to the height where 0 is at gound level. The higher the number the higher the camera, hence the setting 165 gives a height roughly at the top of the airbox.
Direction is simply the direction the camera faces. 0 is directly forward, numbers up to 180 move the camera clockwise an equal number of degrees while a negative number will move the camera counter-clockwise in the same way. Although I haven't tried it I would assume that 180 and -180 give the same result, ie. the camera will face directly backwards.
Pitch is the angle at which the camera will be facing up or down. For the T-Cam view you want the camera pointing slightly down, hence the setting is a negative number, -10. You could have a nice view of the sky by setting a camer to 180.
Roll is the angle at which the camera will lean over. Again the obvious setting here is 0. A setting of 90 will see the camera sat on its side, set it to 180 and you can drive upside down
Damned if I can be bothered to mess around with the other settings available - Detail and Detail 2, and also the 'Unknowns' which remain unknown to me, not that I had ever bothered playing with camera settings until about 20 minutes ago so that's hardly surprising.
See Ya!
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The test of a first-rate intelligence is the ability to hold two opposed ideas in the mind at the same time, and still retain the ability to function. -- F.Scott Fitzgerald