Unfortunately, I haven't yet been able to upload my custom extension using a reliable internet connection.
Every time I try to upload it using my current internet connection the upload fails, which just eats my bandwidth data plan.
In the meantime, I hope the attached script will help you to create such an extension as I am using.
It extracts the extension (and its deps) specified by the -i option from /etc/sysconfig/tcedir/optional into the current working directory and creates an extension with a name specified by the -o option.
deps-merge.sh -i Xorg.tcz -o Xorg-all-deps.tcz