1: Have a working copy of DCS with the modules you fly and a dcs account (Note: You already have this)
2. Have a second PC on your network.
3. Create a new account in DCS world and DL dcs world, and install on your second PC
4. When you boot DCS up, log in using your second account. On that second PC install the missions you want to fly.
5. On that second PC, start a multiplayer server, you can even password protect it if you like.
6. On your first PC start DCS go to multiplayer. Your Server should be the first one on the list or sort by ping.
7. Now fly your mission. Its only on the client that you need the modules you are going to fly.
Hope that helps