This achievement is pretty simple and requires no skill, as all you need to do is play online for 10 hours. The time counted is however not the time taken for the game to finish but rather the time you last within the match. i.e. If you win the round, it's the total time from the word 'go' and when the game finishes. If you lose it's the total time you survived for vs. your opponent(s).
You can check your total play time on the leaderboards, however it's not entirely accurate.
It is possible (and how I did it) to start up/host a game, and with your trusty turbo pad set to repeat on the 'A' button, you are all set to leave it to do it for you. The only downside is that even if you get no lines sent your way you will be out in ~80s and if there are other people playing in your game you will have to wait till they finish before the next round is started. This will slow your progress down.
Ideally you want to find a buddy who also needs the achievement, do as described above and both not be playing. That way though you both only get ~80s per game you will not be wasting much time at all. The game will restart and you will have the achievement between you in about 11 hours, so overnight (and again the next day unless you oversleep)
October 2012 EDIT: This game is now all but completely dead online, so finding someone to idle boost this with is an even better idea than ever.