Dear Covar,
This is another tough one for me because I'm light on the old fashion sense. As far as I'm aware sideburns are NOT in vogue.In fact, very few people can pull off this look without being laughed at or mocked. One other thing you may want to look at is the fact that the Army might not give you as much leeway as you thought. Check your regulations before you do something rash.
Don't do it, man. Sideburns are just weird-looking.