Installation Server works good in RHEL5.3

You can install RHEL6.1 from the RHEL5.3 installation server itself.

1. Create a PXE server. (Refer the blog)
2. Copy all DVD content to /var/ftp/pub/rhel6.1 location
3. Copy the important files vmlinuz & initrd  into the /tftpboot/rhel6.1 location

4. Create kickstart file using system-config-kickstart.

5. Edit the file "/tftpboot/pxelinux.cfg/default" as follows
label 6.1
  kernel rhel6.1/vmlinuz
  append initrd=rhel6.1/initrd.img ks=nfs:192.168.0.254:/var/ftp/pub/rhel6.1/ks.cfg

6. Type 6.1 in the PXE Server boot screen.