My two cents: I'm trying hard, but I just _can't_ put myself in the shoes of Accounting faculty who'd read your application and say "boy, I wish he'd scored 51, but now with 49 he surely is very lousy at math"!
In other words, 740 is great and I think you'd waste your time trying to increase your score by 20-30 points. Being an undergrad in accounting, you have some competitive advantage because you know that stuff already (which most entering PhD students in Accounting don't), but you have to work on your SOP to prove that 1) you have the math/statistics background to succeed at the PhD level (which is awfully harder than GMAT quant), and 2) that you're interested in research. You already have part of 1) nailed but it's likely not enough to _impress_ -- you have the potential to succeed but you have no graduate math courses under your belt yet (real analysis, stochastic calculus, advanced linear algebra..)
Were you planning on Sept. 2006 enrollment? You're past the deadline for most schools in the US. However, if you're looking at Sept. 2007, then you can use next year to take some of these math courses and maybe be a RA for a teacher you had as an undergrad. Good luck!