yes, unzip was possible but not more like untar, becaust it seems to be a initrd ramdisk file now.
I can extract all files with the following command. It is not necessary to unzip the file before!
zcat INITRD | cpio -iv
But the Homeserver will not start, becaus of missing libraries?
/hs/bin/hs_main: error while loading shared libraries: libssl.so.0.9.8: cannot open shared object file: No such file or directory