To whom it may concern.
You can't do a lot without a mouse, but you can load and saves levels, individually or in packs, view the general details and view and change the skills. You can also add terrain and interactive objects, but you can't do anything with the existing ones. Here's the full list:
The keyboard shortcuts are:
alt+f = 'Files' menu
alt+e = 'Edit' menu
alt+g = 'General' menu
alt+t = 'Terrain' menu
alt+p = 'Prefs' menu
alt+m = 'Misc' menu
alt+m = 'Skills' menu
alt+o = Objects' menu
From the 'Files' menu:
l = 'Load level from pack'
s = 'Save level in pack'
r= 'Remove level from pack'
d = 'Load level directly'
v = 'Save level directly'
From the 'Edit' menu:
p = 'Properties'
r = 'Replicate'
m = 'Remove'
s = 'Add steel area'
c = 'Clear the level'
f = 'Bring to front'
b = 'Send to back'
o = 'Select by order', although there's nothing you can do in this screen.
t = 'Select through'. Again, you can't do anything in this menu without a mouse.
u = 'Unselect part'
Nothing can be changed in the 'General' menu, but you can do all that fairly easily with a hex editor if you save the level in uncompressed format. I'll have to find the formatting information again.
From the 'Terrain' menu:
enter = 'Add this'
down or right arrow = 'Next'
up or left arrow = 'Previous'
esc = 'Cancel'
s = 'Change set'
Nothing can be changes from the 'Prefs' menu without a mouse.
From the 'Misc' menu:
a = 'About Lemedit'
c = 'Editor colours', although nothing can be changed in this menu from the keyboard.
g = 'Change graphics'
j = 'Fast screen jump'
u = 'Usage statistics'
l = 'Level check'
From the 'Skill' menu:
1 - 8 for the corresponding skill, and 'enter' to accept or 'esc' to keep the original value.
'Objects' menu works exactly the same as 'Terrain'
Press 'esc' to exit Lemedit.
In every box, press 'enter' to exit and keep changes, or 'esc' to exit without changes.
When a piece is selected, press 'delete' to remove it or 'insert' to replicate it.
As well as being unable to select parts already existing, or view or change steel, you also can't change the Z co-ordinance of a piece, except through 'bring to front' and 'send to back'.
Oh, and
here is the uncompressed file format by R. T.