The two above methods have been patched.
You still get it in customs with 1 controller - Load up CTF, go to settings and set score to win as "1." Pick a map (I went 1-8 in order), start match, capture flag and repeat 8 times (different maps)EDIT:
As stated by "sTk I" & few others - Quicker work around would be to use the Race Game - with Flag Rally as the type and laps set to 1. Takes less than a minute for every map as stated. Only one point is needed to win the match.
"Saturno" Mentioned that quitting the game worked for them in the Race Game Type. This is not something I tested or can test at this point.
Also mentioned that the tracking on xbox is currently broken for this but can be tracked on the Windows Store version of the game.
Tracking should now work.
"Untalmr" Mentioned it is doable on PC version using the quit out method.
You can try it in oddball - Might be faster if you don't know the map layouts too well, lowest score to win is 1:00 possession.