Multirom Install:
1.Format through cwm your sd card to have an ext(Recommended 512 mb)
2.Download the two zips from bigsupersquid posted here:
3.Place them both onto your sd card.
4.Boot into cwm and flash the cwm zip you downloaded from squid's thread.
5.Now reboot your phone and then boot again into cwm(It should have blue text if it flashed correctly and the multirom option)
6.Now I highly recommend you make a backup of your current rom just in case anything goes wrong.(I made a copy of it onto my pc as well.)
7.Now flash the other zip titled "Multirom..." and wait for it to install.Now reboot to see if it boots.If boots then everything has been done correctly.

Rom on SD Card


For this I have install on phone the latest build of cm for oV and will be using the same rom to setup on sd card just for test.

1.Now here Make another backup of your current rom through recovery(Will be used trust me)
2.Now flash the rom you want to use on sd card.(If using a 2.3 rom then the sd card crom msu also be 2.3 and vice versa for 2.2 roms).Reboot phone(a must so dalvik is created correctly).(Make sure to do the appropriate steps fro flash rom like wiping etc.)
3.Reboot back into recovery.Go to multirom and select "Create from current rom". (flash the multirom zip again if it says folder not found)(ROM on the sdcard is placed in /sd-ext/multirom/rom/).
4.After it finished you can go ahead and restore the backup you made in step 1. and the reboot after finished and wait until boot manager shows up.
5.Select boot from sd card and it should boot into the rom you chose to install to sd.(If it doesn't then you did one of the steps wrong).
6.That's it you now have multirom booting enjoy it !

MultiROM recovery menu


Active/deactive state is for recovery only, you can boot ROMs from backup in boot manager - that means its N-times boot rather than dual-boot.

When not active(boot from internal memory):
Activate (move from backup) - when you already have backup, this will move it to active folder (fast).
Activate (copy from backup) - same as above, but it copies it instead of moving
Create from current ROM - pretty self-explanatory
When active(boot from sdcard):
Deactivate (move to backup) - Moves current ROM to backup folder, so next boot will be from internal memory
Backup - Creates backup of current ROM
Erase current ROM - Deletes current rom, next boot will be from internal memory
Copy modules from int mem - Copies modules from ROM in internal memory to SDcard. Try this if WiFi does not work in SDcard ROM.