Xmodmap: Swap Alt Ctrl keys, capslock AS control, shift-capslock as capslock.

.Xmodmap

! See keys with:
! xev
! Clear memory:
! setxkbmap -option
!
! Use this file:
! xmodmap ~/.Xmodmap
!
!setxkbmap -layout gb -option ctrl:nocaps

!xmodmap -e "keycode 9 = Caps_Lock NoSymbol Caps_Lock"
!xmodmap -e "keycode 66 = Escape NoSymbol Escape"
keycode 9 =  Caps_Lock
keycode 66 = Escape

clear control
clear mod1

add control = Control_L Control_R

add mod1 = Alt_L
!add mod5 = Alt_R


! Make LeftAlt  -> LeftControl
keycode 64  = Control_L
! Make LeftCtrl -> LeftAlt - you need the add and clears above for these to work
keycode 37 = Alt_L

! Make Alt-GR -> LeftAlt
!keycode 92 = Alt_L