I want to set up the latest Bitcoin Core version to mine a block that is valid after the BIP-110 is activated (two months from now). What are the steps to do at minimum? I want to make sure that a block is not rejected by the Bitcoin P2P network.
BIP-110 specification: https://github.com/bitcoin/bips/blob/master/bip-0110.mediawiki
I understand you may be enthusiastic about the BIP 110 soft fork proposal, but it's important not to take its activation on the Bitcoin network for granted. The proposal's questionable objectives, inconsistent technical design and reckless deployment have had very limited success in convincing the Bitcoin economy to adopt new consensus rules.
I am aware that advocates of the proposal really only aim to deter miners from confirming transactions matching certain (arbitrarily defined) characteristics. As such they see a minority of community-run full nodes restricting the set of valid transactions as sufficient deterrence. But Bitcoin (thankfully) relies on economic incentives rather than defining validity as the intersection of the sets of transactions each participant finds tolerable.
As such it's important to understand that without a substantial part of the economy enforcing the new consensus rules, miners would have no incentive to leave fees on the table for transactions that the overwhelming majority of the Bitcoin system considers to be valid. Going further, miners that self-censor would be at a disadvantage compared to miners that include all valid transactions there is demand for. This is the fundamental mechanism by which Bitcoin provides censorship resistance: miners will eventually give up censorship or go bust.
This mechanism is of course not bulletproof, but it's not so weak as to let consensus rules be defined by the most intolerant minorities of Bitcoin enthusiasts. Otherwise Bitcoin would be pointless, since you can always find a minority that does not like another's transactions.
Therefore in August full nodes rejecting current Bitcoin consensus rules will inevitably fork on a different chain. In fact, it is more likely than not they will simply stall, given the small amount of hashrate signalling its intention to heal a Bitcoin fork with BIP 110 rules.
Bitcoin Core nodes do not enforce the BIP 110 rules and will continue following the Bitcoin chain. Thus mining a valid Bitcoin block after the BIP-110 full nodes start rejecting the chain would be no different than before. There is also no feature in Bitcoin Core to create a block template that specifically doesn't include the arbitrary set of transaction BIP 110 considers to be invalid. I also don't expect the current set of Bitcoin Core contributors would be interested in maintaining such a feature.
Disclaimer. I personally consider BIP 110 to be extremely misguided. I contribute to Bitcoin Core and can't speak for the project, my own perception of what features other contributors would be interested in maintaining may be erroneous.