Does KH support the Xaraya CMS? Can it be installed by a user either through an interface or manually?
No this can not be installed on shared hosting.
Xaraya is platform independant and can be configured on systems that are running Linux or Unix, BSD, Mac OSX, Solaris, HP-UX, AIX, Sun Cobalt OS (RAQ4) or Windows98/XP/NT/2000 operating systems.
May be because of this line
CentOS is not included.
But still if Linx/Unix is there, it should work with CentOS also