The "magic pixie dust" would probably be excellent engineering & gear from start to finish.
A band-aid solution (high-class EQ, multi-band comp, etc.) can't compete with a high-quality signal chain, great console/room/monitors, and experienced engineer.
I've seen a number of clever people here in town mix their latest record themselves at home on their MixPlus, then go blow $$$$$$ at Grundman or Weinberg or whatever trying to get that expensive sheen at the end because it still didn't sound like a record. Much time and dollars later, they were frankly disappointed with the overall result. Some of them didn't use the expensive mastering and ended up re-mixing their album in an SSL room with an engineer. So much for the DIY shortcut.
Moral of the story: Great mastering can't always make up for all the rest.
EQs you can rent in to try to DIY:
Millenia dual topo stereo EQ GML 8200
A pair of Pultecs
Don't forget great converters if you're working on a mix stored to digital.