Ok, let's see to clarify things for positioning issues, then you ask other things, I'll try to solve them.
Well, initially you have to download Tweaker 1.0.4.5 Reloaded.
Then open your MOD folder, go to Patch folder and put EnableTweaker.cap (you can find it in other MODs, or in ZaZ Tools dir under Extras I guess...).
Go back to your MOD main dir and create a new folder: call it Tweaker (or whatever you want); here put gp4tweak.dll, gp4tweak.ini and gp4tweak_data, sprite folders you find in 1.0.4.5 compressed file you previously downloaded.
Now go to Settings/swap.ini in your MOD and put lines like these:
[Swapfiles]
...
File8 =Tweaker\gp4tweak.dll,gp4tweak.dll
File9 =Tweaker\2008\gp4tweak.ini,gp4tweak.ini
File10 =Tweaker\gp4tweak.bin,gp4tweak.bin
[SwapFolder]
...
Folder5 =Tweaker\2008\gp4tweak_data,gp4tweak_data
Folder6 =Tweaker\2008\sprite\visor,gp4tweak_data\sprite\visor
Folder7 =Tweaker\2008\sprite\visor\dirt,gp4tweak_data\sprite\visor\dirt
Ok, first part done. Take a rest.
Let's go to gp4tweak.ini in your Tweaker folder and open it. Set:
HelmetPos = 1 ; set to 1 to enable helmet position tweak
TyrePos = 1 ; set to 1 to enable tyre position tweak
(initially they should be 0 instead of 1).
Go to gp4tweak_data\helmetpos.ini and gp4tweak_data\tyrepos.ini (follow obviously your Tweaker path in the MOD), and modify values with the ones you want to use.
Save and run the MOD and see what will happen.
Bye
ROAR