Just bite the bullet and buy the proper tool, saves a lot of hassle in the long run. There are a few different carb balancers out there, so just do your homework. I find the Carbtune works well and no mercury or other odd du dads to mess around with.
The old saying, " that there is nothing cheaper than the rider ", is true in a lot of cases, and I'm guilty of that from time to time. Good tools will last you a lifetime and make the job so much easier.