Background: Morello was born on May 30, 1964, in Harlem, New York, to Ngethe Njoroge and Mary Morello. Morello, an only child, is the son of an American mother of Italian and Irish descent and a Kikuyu Kenyan father. His mother was a schoolteacher from Marseilles, Illinois, who earned a Master of Arts at Loyola University, Chicago and traveled to Germany, Spain, Japan, and Kenya as an English language teacher between 1977 and 1983. His father participated in the Mau Mau Uprising and was Kenya's first ambassador to the United Nations.
Context: Morello is famed for his guitar style, which consists of heavy metal/punk hybrid riffs and hip hop-inspired sounds. A 1993 Melody Maker live review of a Rage Against The Machine gig, said "Guitarist Tom Morello wears his guitar high up to wring every sound out of it. Falling bombs, police sirens, scratching - he can do them all."  To produce his guitar sounds, Morello chooses various effects pedals. During his tenure in RATM, he used a Dunlop Cry Baby, a DigiTech WH-1 Whammy, a Boss DD-2 Digital Delay, a DOD EQ pedal (set flat and just used to boost the volume during guitar solos or particular rocking moments), and an Ibanez DFL Flanger. Around the time of The Battle of Los Angeles he added a Boss TR-2 Tremolo pedal (which can be heard on "Guerrilla Radio"). For Audioslave, Morello replaced the Ibanez Flanger with an MXR Phase 90. His amplifier of choice has always been a 50-watt Marshall JCM 800 2205 and a Peavey 4x12 cabinet. While the Marshall amplifier has two channels, he only uses the overdrive channel, and simply lowers the volume on his guitar to get cleaner sounds.  In the studio, Morello uses the same setup for the bulk of the guitar tracks. For The Battle of Los Angeles, he also used a few other amplifiers, such as a Line 6 as heard on the clean, spacey intro of "Mic Check", plus a Pignose mini-amplifier and a MusicMan "Twin" style amplifier. During the recording of Audioslave's last album, Revelations, Morello experimented with different amplifier setups. For the title track's solo he split his signal to his standard Marshall 2205 head and Peavey cabinet and a 100 watt Fender Bassman head and an Orange cabinet. With delay sent to one while the other is unaffected the sound is being "ping-ponged" between the two amplifiers. He also borrowed a Vox AC30 amplifier from producer Brendan O'Brien for some tracks.  Morello's unique technique and talent led to him being voted the fifth greatest guitarist of the past 30 years in a 2010 BBC poll.
Question: How did he learn this method?. Whats the answer?