Thumbs down [Q] How to enable LTE BAND 7 (2600 MHz) on NEXUS 5 LG-D820

Hello guys.
I've been reading many posts here about my question, but did not find any conclusive and/or step-by-step answer.
So, the thing is I bought a NEXUS 5 D820 and, here in Brazil, the LTE network is just in the BAND 7 (2600 MHz), which is not included by factory in the D820 (just in the D821).
Some posts said i can flash the modem of the D820 so I can enable the LTE band 7, but i really dont understand how.

So, someone can help me?