I resolved my issue as below, the idea is to reuse 32bit installation extlinux boot, and update files/pkgs from 64 installation(boot file from CD, pkgs from HD).
1. Boot VM1 (from CorePure64 CD +sda1(has my installed 64bit pkgs)), so the /mnt/sda1 is mounted
2. mount CorePure64 CD to /mnt/sr0
3. mount my VM2 HD(32bit text only installation HD) to /mnt/sdb1
4. copy sr0/tce/boot/corepure64.gz and vmliuz64 to sdb1/tce/boot
5. edit sdb1/tce/boot/extlinux/extlinux.conf to use corepure64.gz and vmliuz64
6. move sdb1/tce/optional to sdb1/tce/optional32/, and move sdb1/tce/onboot.lst to onboot32lst.txt (backup for now, I will remove it later)
7. copy sda1/tce/optional folder and onboot.lst to sdb1
8. power off VM, disconnect CD and VM1HD, reboot with only VM2HD