These make little or no sense:
find --set-root /ISO/checkn1x-1.0.5.iso || map --mem /ISO/checkn1x-1.0.5.iso (0xff)
map /ISO/checkn1x-1.0.5.iso (0xff)
What you are telling grub4dos is:
1) look for a file and establish root where the file is found
2) IF the file is NOT found (and thus root is not changed), map in memory the file (which was not found) from current root (that was not changed) to device 0xff
3) map anyway the file (that was either found or not found) from current root (that may or may not have been changed by the find --set-root command) to device 0xff
Maybe you meant something *more like*:
find --set-root /ISO/checkn1x-1.0.5.iso
map /ISO/checkn1x-1.0.5.iso (0xff) || map --mem /ISO/checkn1x-1.0.5.iso (0xff)
or
find --set-root /ISO/checkn1x-1.0.5.iso
map --mem /ISO/checkn1x-1.0.5.iso (0xff) || map /ISO/checkn1x-1.0.5.iso (0xff)
I.e. essentially try directly mapping the file and if it doesn't work try mapping it in memory or viceversa.
With some Linux distros, some "kernel parameters" or "cheat codes" are needed (like the "findiso=/ISO/checkn1x-1.0.5.iso" you used, that may or may not be valid for the specific distro/tool/release), otherwise you need to use the (more complex) partnew (fake iso partition) trick, see here:
http://reboot.pro/in...ic=9916&p=88531
Steve6375 has almost fully automated the approach in his Easy2boot tool, but it has to be tested if your particular .iso iworks this way "as is" or - say - it needs to be de-iso-hybridized (basically removing the partitoning from first few sectors of the .iso, i.e. having the first 16 - 2048 bytes each - sectors of the image blank).
Wonko