Use the find function (ctrl + f on Windows if you're unfamiliar) and type in 'human=yes' to find the information on your country (I will use Russia as an example).

In order to unlock the communist party, you need to edit the save file. The only hitch is that the communist party won't be unlocked at this point, so you'll be stuck with (probably) the reactionary party until around 1880.

It's either 60000, or 60x00 where x is a number from 1 to 9. In order to become communist, you can type in 'event 60000'.