by 
While I'm at it, I've heard of a convenient way to help grind these things out. I don't know if it's ethical or not but, I'll leave that decision to you.
1.) Start a server
2.) from console: mp_teams_unbalance_limit 0
2.) from console: sv_cheats 1
3.) from console (as many as you want): bot -team red -class scout
4.) from console: sv_cheats 0
5.) from console (DO NOT FORGET TO DO THIS!!): retry
6.) EARN YOUR ACHIEVEMENTS
7.) from conosle (just in case as some achievements require death): kill
8.) You're done.
Notes:
This turns cheats on to add the bots, then turns it off. The retry tells the client to retry the last connection which will allow the client to detect that cheats are not on anymore (which means you can earn achievements). The bots will stay after the retry command.
To move them around you can use the console command: bot_mimic
bot_mimic 1 turns it on, bot_mimic 2 turns it off.
The only reason I know about it is because I don't have a large set of steam friends and some of these achievements can't be earned. Again, just disseminating information. I don't know how Valve views this practice but it seems ok in my book (that and 5 bucks will get you a coffee at Starbucks) so don't shoot the messenger.