- In the OS settings, go to "keyboard" and select a "Compose Key." I like to use "Print Screen"
- Edit (or create) ~/.XCompose to include the following:
# Capital Letters
<Multi_key> <G> : "Γ"    U0393    #  GAMMA
<Multi_key> <D> : "Δ"    U0394    #  DELTA
<Multi_key> <L> : "Λ"    U039B    #  LAMDA
<Multi_key> <P> : "Π"    U03A0    #  PI