Not so long ago I found the magic to get a UK type 5 set up correctly.
(I don't remember how.) In XF86Config-4, I have:
Section "InputDevice"
Identifier "Generic Keyboard"
Driver "keyboard"
Option "CoreKeyboard"
Option "XkbRules" "sun"
Option "XkbModel" "type5"
Option "XkbLayout" "gb"
Option "XkbOptions" "ctrl:swapcaps"
EndSection
Have you tried something like that with "fi" instead of "gb"?