First is getting them expanded, then do a slurry test on a sample to make sure they're not salty.
Then, assuming they don't need to be flushed (I've only ever had to flush my used coir, back when I was using chemical salt ferts), it's time to charge them. You want a mild vegging solution, about 250ppm if that's how you're rolling, and a qualified metric shit-ton of Ca. So for example let's say I'm using a 6% Ca like BioLink, and it says to use 5mls/gal for regular feeding, you'll want to go with 20mls or so because your goal here is to get ALL available sites (molecular) filled with Ca so that when you give your plant Ca the coir doesn't instead latch onto it. That's the biggest problem with coir.
Once you've done that, you should be good to go.