Well, I think I am in the right way, now the thing is related to permissions
I modified skypeforlinux.desktop to add /local/ to the Exec parameter
and then moved all the files in /usr to /usr/local and then redid the mksquash process
now I have the "Skype" item in apps menu, but attempting to launch it does anything, in the log file shows:
nohup: can't execute '/tmp/tcloop/usr/local/share/skypeforlinux/skypeforlinux': Permission denied
doing a ls to the binary says this
tc@box:~$ ls -la /usr/local/share/skypeforlinux/skypeforlinux
lrwxrwxrwx 1 root root 69 Apr 30 19:58 /usr/local/share/skypeforlinux/skypeforlinux -> /tmp/tcloop/usr/local/share/skypeforlinux/skypeforlinux
My guess is about the owner of the file, but don't know exactly what to do