Well, as I promised, here we go...
Everything is located inside of exe file, so open up your exe with some hex editor such as Hex Workshop.
Now, the following ones are the startings offsets for each of these games...
7219831 - PES 5
7210927 - WE9LE
8008039 - PES 6
Just use go to function and type in offset to get you there immeadiatly.
Now, here you'll see screen like this:
You'll notice the 0000 0000 bytes - these are the ones you're after...(the first 8, ignore the last 2)
First 0000 is used for national team registering and second is for emblems...
Here is screen of what you only need to change, don't mess with other bytes...
And so on and so on, you get the point.
What you have to do is change these offsets with numbers of team you want to overwrite over them, you can easily see what number is team you want to make with DKZ, just switch to nationalties tab and count, afterwards use this free decimal to hexadecimal converter to convert it to hex number
Here is my example
I want to overwrite Austria with Bosnia and Herzegovina.
BiH is right after Australia and Australia has ID 56(you can see that in kitserver to make it easier for you to count) so BiH has 57.
I type in 57 in hex converter and I get 39.
I overwrite 0000 0000 values with 0039 0039 and I save the exe. That's it, just run the game and see the changes for yourself, it's same for every other national team including classic teams, they are ordered the same way they are in kitserver
All credits go to ME (damn I'm cocky ) Kristian826