Don't. All the colleges on Daley Rd. (I don't know if you've visited campus, but Daley Rd. is where all the colleges are apart from Fenner and UniLodge) are super competitive in that they have fewer spaces than they have people applying for those. You are in an okay position in that it will obviously be possible for you to get a place in one of those colleges, because you satisfy the university accommodation guarantee (lots of people don't but still apply anyway because they really want to live on campus).
With Burgmann, you're right in that there is no guaranteed way to get in. However, you can increase your chances quite a lot. What you should do is email or fax a kind of 'cover letter' to the Principal explaining why you want to live at Burgmann, but more importantly, (and this is absolutely crucial) what you will do for Burgmann and how you intend to be involved with Burgmann and help Burgmann as a resident. You don't get enough space to write this stuff on the application, so if you go out of your way to do something extra, they'll be able to actually separate you from the hundreds of other applications they'll get for roughly 100 spaces.
Another method that has worked in the past - phone up the principal and say that you'll be overseas when offers come out and you'd like to know if you could get an early offer. This is more certain in that you'll know by the end of the conversation if you got a place or not. However, it might not still work.
What happens with the allocations is that if you get knocked back from your college of choice, you then go into a completely random draw. You might get something good, you might not. Additionally, know that people who spent a semester in a hotel always eventually got into a hall in the mid-year because heaps of people move around. I also know someone who got into UniLodge but wanted Burgmann, so she was pretty much at Burgmann everyday asking if any spaces became free. Two spaces opened up by week 3. It's not an ideal situation, but you certainly don't have to give up either. Besides, the hotel deals look pretty sweet to me - you get food vouchers for a restaurant for every meal and a free bus pass (it's costing ANU a lot of money!).