If you request a game or series, you're automatically set in place as mod for that series/game, Mods can "name" other mods on their own accord after that, so if you're interested in becoming mod for a specific game, just ask the current mods - unless there is no need for a new mod, there's a high chance you'll be elevated to that position.
We have a WHOLE THREAD about Moderating in the "Site" forum. https://www.speedrun.com/The_Site/thread/qkvjz
~HDK
Recently, there has been a lot of confusion and wild rumors going around about this topic, so I'd like to finally put this argument to rest. To ascend to the realm of moderator, you must boot up Ocarina of Time, find the Triforce, then use it to complete "Through the Fire and Flames" on Expert mode. This will spawn a MewTwo, which you must catch without using the Master Ball. After the battle, go to the menu, and you'll see that it's holding a copy of Mega Man X. If you can manage to distract MewTwo long enough to take the SNES from him and beat the game without taking any hits, you will receive a personal invitation from i_o_l to beat the high score of "You Have to Burn the Rope". Thus, the possibility of anyone ever becoming a moderator has been officially disproven, because nobody is ever going to beat that stupid score.
Please don't seek modship because it's "cool." Seek it because you want to be a leader for a community and/or caretaker for a board.