You must make your way to Nellis AFB and befriend the Boomers.
When approaching Nellis AFB, you must dodge a barrage of artillery shells, which do a substantial amount of damage. The Boomers fire in 14 round barrages. Alternatively, you can bypass the artillery by gaining access to the train tunnel to the southeast (100 Lockpick skill).
Also, expect to encounter deathclaws on the approach to the tunnel entrance. Once on the other side of the tunnel, it is possible to still be bombarded by the shells.
Upon reaching the gate, you will be allowed to enter Nellis AFB and you must complete the quest Volare! to earn fame from the Boomers. Once you have completed all the quests for loyalty and have earned the status of Accepted, talk to Pearl, and this portion of the quest will be complete.
Note: If you have already become Idolized by The Boomers but have not completed the Volare! quest raising the B-29 from Lake Mead, you cannot complete this mission the non-violent way. The speech options don't come up with Loyal or Pearl, they just refer you back to their quest. If you have already become Idolized by the Boomers, you will still need to go see Pearl to ask for their support of Mr. House, which you will be able to earn. Then you can report back to Mr. House.
If you choose to neutralise the leadership of the Boomers, do the following:
Once you get past the initial bombardment when you approach Nellis Airforce Base for the first time, walk up to the gate and talk to Raquel. As long as you keep choosing the top option she will take you straight to Mother Pearl. Once you have finished, you just have to kill Mother Pearl how ever you like but doing so will grant negative Karma as well as failing the side quest Young Hearts. On her corpse you will find a 40mm grenade launcher with 30 40mm grenade and some frag grenades.
Please note killing Mother Pearl will cause all the Boomers to become hostile.
Next, you must kill Loyal. He is located at the Nellis Hangars, which are slightly north from Pearl's barracks, or he may be in his house to the west of the Hangers. He is not very difficult to kill on his own, but there may be a problem if the Boomers are hostile, or if they turn hostile after having killed him.
After you have killed both Pearl and Loyal, return to Mr. House and inform him of what has happened to move on to the next part of the quest.