Ok.. keep in mind that the shelflife, even when refridgerated isn't very long.. something like 60 days or something.. (forgot from the Organon Pregnyl insert)
I have run 5000iu at 500iu/week before.. 10 weeks.. which is a tad over the recommended time to use the solution once reconstituted... **don't get me wrong, you can run HCG for long cycles, but we're talking about individual amp's shelflife once mixed***.. So, I did it, but I didn't get sick.. I could be superhuman though.. I haven't seen anything to tell me otherwise.
back you your question.. I think this will aid you a little bitter..
buy small sealed/sterile vials. You can even get 2ml sealed/sterile at a certain research lab supply store I know of

.. 10ml will do fine and you can find these anywhere.
So you have the BW, and the 5000iu amps.. now you have small sterile/sealed vials. perfect.
You'll need 1 or 2 basic 3cc syringes with any guage needle, but 1 1/2" in length... plus one more needle (needle only)
1- crack the amp comtaining the HCG powder
2- suck up 1cc of BW (sometimes you get 1 amp of BW with the kit, but you sound like you have a multidose bottle)
3- gently squirt the 1cc of BW down the side of the HCG amp, it will mix instantly.
4- Suck up the solution that you just mixed, inside the same syringe
5-insert the solo needle I asked for into the butyl stopper of the small vial you acquired. This is to vent the air and equalize the pressure when depositing the solution inside.
6- squirt the 1cc HCG/BW solution from the syringe into the small vial you just pierced with the needle, gently squirt it down the side for the sake of it.
7-you now have 5000iu/ml of HCG.. way too concentrated for efficient dosing. We are now going to dilute it for easy dosing.
**** THIS IS WHAT I WOULD DO BECAUSE I FOLLOW SWALE'S 500iu/WEEK PROTOCOL*****
8- Add 4ml of BW to the vial you just put your solution into, use the second syringe I asked you to have because you might contaminate the BW multidose vial if you use the old syringe... you now have 1000iu/ml concentration..
Now you can take a slin pin, and draw up to the 25th iu/tick/gradiation mark on the barrel, and have 250iu to dose on saturday, and then on sunday.. this will last you 10 weeks... which I personally can get away with, but I feel is over the recommended shelf life of reconstituted solution.
Now please go spread love in your city,
Ubiquitous