Make a text file, add this sole line
BMOUSE.EXE LAUNCH blood.exe
save it as start.bat. When you start dosbox and then enter the mount commands and then cd to your blood folder, don't run blood.exe, but start.bat.

{My apologies about the double topic, i though I didn't successfully create this one that's why i took the liberty of starting a new one}

It seems like that the file was still a text file for a reason that i ignore (Probably because i'm stupid).
The problem now is that it doesn't launch the option that i saved into the config file. I need to add something else i bet but i'm not totally sure ?

Can you be more specific when you talk about text files and cfg files and which settings you entered into some cfg file?
Because there are two config files, the Dosbox preference file and the blood.cfg file. And the Dosbox preference file is also dependent on the Dosbox version you use.

Sure, I'll do my best.
The bat file that you you told me to create is now working.
Now I have another problem, the game is lauching well but with basic settings.

- - -

I'm using DosBox 0.74.
I made some change into both, the blood.cfg and the DosBox preference file. When the game launch, the settings aren't the same that it was when i launched the game without using BMOUSE. (For instance there's a problem of memory that weren't there before so i bet the problem is from DosBox and not the blood.cfg)

Starting from the start.bat does not affect Dosbox settings, these should be the same either by starting via the batch file or blood.exe.
Everything that is different isdue to the bmouse and/or what you didto the blood.cfg