This is how I use HCG. I mix the compound with the water, after doing so I pull it all out in a 3ml IM syringe. Once the solution is in the syringe, I take the needle off of the syringe and push the plunger to where there is no air inside (hold it upright so it doesn't pour out of the hole where the syringe goes).
Then I take my slin pin and put the slin pin needle in the opening of the IM syringe and draw what I need. So you can put 5000iu in the syringe and take out as much as you want, when you want it. Keep the IM syringe with the HCG stored in the fridge. You can also do this using a sterile vial and draw from there....but syringes are easier to come by than sterile bottles.