Is there a way to edit the game files to unlock all the missions?

[Saethwyr]

I'm using the GOG version (Gold)
I've played through the game a million times, recently re-installed it but there's a particular mission that I'd like to play through and I'd rather not have to play through all the missions beforehand to get to it.
I found a 100% completed savegame for download online but that's only for the three Art of Conquest campaigns, and I'd like to unlock a mission from the Greek campaign.
Thanks

[ArmageddonNY]

Just use cheat code!