A simply won't work is not enough information...
Some logs? Some error descriptions? Some detailed description of what you are doing, what happens and what should happen?
i create this post 'cause i need to copy my binaries to a remote target device (i'm running C::B on windows)and also launch gdbserver from the host.
This sounds like your remote target is not a windows host? Some detailed description of the host, target? What connection are you planning to use?
[EDIT:] Sorry, i over read the title... Your question is to run a script before the debugger on the target? My questions above are still valid.