It seems there is a big difference between all the tutorials, each refers to a un-certain IDE version, and files to edit simply don't exist anymore.
It shouldn't be so bad. The ATmega8 bootloader hasn't changed much recently, especially "what files are where." (in fact, the atmega8/ATmegaBOOT.c that is in 15 is exactly the same as the one in 10.)
"bash:make:command not found"
What/how/where to install the commands...
i'm on macosx.
Ah! I suspect that the big problem is that the people who have written the instructions and who are offering you advice have the MacOS "developer tools" installed, so they already have "make" in expected places. It looks like starting in ardunio-0012 there is a version of make included in the arduino distribution...
Next , where do i change the DF CPU= 4000000L?
In the bootloaders/atmega8/Makefile, there is an "obvious" -DF_CPU=16000000 that should be all you need to change FOR THE BOOTLOADER ITSELF.
So, the easiest path to getting a 4MHz bootloader is probably:
Download Arduino-0010 so you have the right version of the C compiler.
Download Ardunio-0012 so that you have make.
Edit arduino-0010/hardware/bootloaders/atmega8/Makefile to change the clock frequency (and fuses?)
In a shell window (terminal), cd to arduino-0010/hardware/bootloaders/atmega8/Makefile and type
(Replacing "/Downloads" with whatever prefix is appropriate for where you put the arduino installs...)
I don't know if it's any comfort, but this sort of flailing around is exactly the sort of thing that the Arduino environment is supposed to prevent. You just happened to have your needs fall outside of the "easy" area.