Its easy. What isn't really clear, especially if you are running a rack on X32 Mix is that
FX1-4 are sidechain/insert, and FX 5-8 are inserts.
XMIX screen
So all you have to do is pick your 31 band eq, and put them into FX 5-8
Since each one is a dual 31 band, you set the BUS to which ever one you want to go to what EQ.
So in the above example, you'll see I have bus 1&2 going to FX slot 5 (insert) and they FX is selected (purple) to activate it. Now bus 1 & 2 have a 31 band inserted. You can EQ your wedges.
You'll see FX slot 6 has bus #4 going to it, an i have channel 5 with a 31 band inserted.