I talked to my doctor about it, and they recommended pulling from the ampule into a 10mL luer lock syringe (through a filter to be sure you don't have any glass fragments). Then fill a set of smaller luer lock syringes to the level needed. (Without a needle on the receiving syringe, you can easily inject into it. Just hold the plunger, or it will magically increase your dose.)
The resulting dose syringes get wrapped in foil -- cerebrolysin is light sensitive -- and refrigerated.
I've since come across a video from another doctor explaining the exact same process.
Oh, and it looks like you can get 5mL ampules, which seem to be intended primarily for IM.