Unfortunately rote memorization is about it, but the good news is.....ACLS has become a lot less intimidating over the years and they are now letting you take cheat sheets or actually algorithms into the testing station with you. You will feel much more comfortable though with a good understanding of the meds. The main ones are atropine, epi and the antiarrhymics. The good news in the megacode is that no matter what the rhythm is, it will more than likely deteroriated into PEA or asystole and then it is easy!
Know your heart blocks and how to treat them. Some you don't treat, some you pace and some you treat with meds.
If you take each med and make a chart of doses, route, etc. you will see that they are very similar and really not a lot of wide variations. Sit down and make drug cards like nursing school
, but just put very basic info, you don't need much. Then from the cards, make a chart based on what drug, what useage and what route. I think you will see it is not that difficult if you break it down. Good luck and try not to stress too much, they want to make you learn, not fail!