Use the below link to access arm dCore:http://tinycorelinux.net/dCore/armv7/
And if that TCZ has no dependencies, just rename it and it will become an SCE. There is not a command to convert a debian package, it is an involved process. But to put it in a nutshell, below will convert a Debian package into an sce or tcz:
ar -x package.deb
tar xvf data.tar.gz -C pkg
mksquashfs pkg extension.sce ( or extension.tcz)
That does not take into account startup scripts, but can help if offline and needing to convert a .deb to an extension.
There is dCore for x86 also that has importsce if that is what you are asking.