Hello there, I was frustrated a little when it failed first to start. However by means of tries and sufferings I've found a way to put in on.
Find the directory of game (most of all it is ~/Library/App Support/CrossOver Games/Bottles/angels(in my case)/drive_c/Program Files/Angels Online/
you only need the file 'midage.ini' open it with a common textedit the edit (copy/paste) the following strings:
GameWndSizeWidth = 1024
GameWndSizeHeight = 768
GameWndFullScreen = 1
I believe you could easily play with the resolutions however pls find out more in game settings it could not be support the 1440x900 and higher res.
have fun!