I've been using a 1604 for monitoring in the studio for years. I've finally gotten enough outboard preamps so that I don't have to use it for it's preamps, thank god.
Anyway.
I'm not sure why you actually read what the console says. Do what you want. That board is about as flexible as any budget board. Just because it says "control room" doesn't mean you have to use it for that. Actually, I never even tried that now that I think of it. I'm pretty sure the "control room" tag is put on there so you know what room to put it in.
Here's what I do. I can get 5 different headphone mixes with the Mackie and some cheap Behringer headphone amp. I feed the Behringer with my aux sends.
Normally, I monitor through my Mytek DA96, but when tracking I send the output to tracks 1 / 2 of my Mackie. I have my studio monitors running off the RCA Main outs although 1/4" would do just fine. I use the master fader as the master volume for my studio monitors in this situation.
I then run Bus 1 /2 to the headphones.
I also like when I'm recording a quite instrument like vocals to run the vocals through an extra mic into my Mackie and run it to Bus 3 / 4 so that I can listen to their performance through my monitors.
So with that in mind, the Mackie is capable of 6 different mixes at the same time, 5 headphones and 1 on the studio monitors although the studio monitor mix is not all that flexible.
I recommend that you take a look at all those outputs in the back of that mixer. You have quite a few options.
Brandon