The two repositories you are pointing yum at are only "raw" trees with rpms/srpms so I created an empty comps repository containing the comps.xml file and repodata needed around it (for my first test with appliance-creator some days ago) :
Thanks. That worked. I am facing one problem though I did
yum --installroot=/tmp/temp install kernel
but there is no initramfs in /tmp/temp/boot Any idea what might be going wrong?