Any special reason you want to use extlinux?
In version 3.6, the installer has been improved.
I have written a number of installation guides in the wiki, using the improved installer.
If you install using the installer, using a Linux filesystem, it uses extlinux.
Many people want to dual boot, Tiny Core and Windows.
I know it can be done using Grub, I wrote an installation guide on that too. But installing grub, makes the process more complicated for new users.
If there was a way of just adding Windows boot commands to extlinux, that would be much easier.
I am not sure what is possible with extlinux. To boot extlinux the partition needs to be boot or active. To boot Windows the partition needs to be boot or active. Only one partition can be boot or active.
But it may still be possible. I was hoping someone may know.