Rob,
With the old-skool ALICE gear, the front suspenders straps clip to little tabs with eyelets on the magazine pouches.
It is good practice to place your magazine pouches slightly forward from your hip bones. Mine always rode pretty much over the front slash pockets on my BDUs. This allows you to go prone (lay down) and get as low as you can. With the design of armor-based MOLLE LBE these days, goin' prone ain't as easy as it used to be.
I have a Blackhawk STRIKE MOLLE rig which I have set up like web gear using old woodycam MOLLE II pouches. It's much cooler in tropical environments when you're dismounted than a vest system and allows you to go prone more effectively.
But having said all that, unless you've got someone who's gonna yell at you because your ALICE gear don't follow unit SOPs, experiment and find the best way for your needs.
A bit of advice though for your ALICE setup - a buttpack and 2 x canteens is good practice.
Since I'm mainly planning a bug-in, in an urban environment my ALICE load is going to be light. For short duration missions, i wont need mag pouches as except for the 1911 as I'm going to go with a tactical shotgun based rig with a 53 shell bandoleer, over the top of everything. (
http://www.eagleindustries.com/product.php?productid=55&cat=40&page=1) The belt is going to have a 1911 in a shoulder holster attached to the web belt, 1st aid kit, 1qt canteen and alum cup, my two ka-bars: a smaller Tanto style and the giant D2. MY urban man-purse will be repurposed to attach to the web-belt:
http://www.maxpedition.com/store/pc/viewPrd.asp?idcategory=4&idproduct=54
You can cinch it up tight, and I might just use the built in holster instead of the shoulder rig. It also has space for a quart nalgene bottle I'd also use it to hold emergency provisions.
But really, what I'd like to do is get one of these:
http://www.cheaperthandirt.com/MOLLE704-1.html
I'm pretty sure I could attach it at the back of my ALICE rig around the Y, yoke, and also on my french surplus rucksack thats not MOLLE either.
Other then that I'm looking at a Camelbac and thats just two dang many layers of shoulder straps.
-Rob