I don't believe you need a macro to do this, instead depending on your OS you can map a FTP or other type of protocol remotely.
For example in windows you can "Map" a FTP as a drive and this would do exactly the same thing as your describing, you open the file from the FTP and upon saving it will then be written to the remote server. FTP is just an example here, there are other platforms you can use.
If you are at all interested in this method then following the instructions below, otherwise disregard.
Mapping a Network Drive in Windows Vista and 7.
- Click on Windows start orb and then click on "computer".
- Click on map a network drive.
- Map a network drive will then open a new dialog box where you can click "connect to a website"
- Simply follow that easy to use wizard and click add a new network location (Choose a custom network location)
- Type in your FTP address, including username and password.
- Finally name your network location to whatever you want.
Just a suggestion, I really don't think you need any macro unless you plan on distributing these files to other people then yes, but they would need to install that macro/plugin on their open office since there is no way to encode the document itself with such features as far as I know.