Tricking Wubi into installing Xubuntu 12.10

Xubuntu is no longer available on Wubi from release 12.10 and later - as I mentioned here: Xubuntu option to be removed from Wubi. However, there are some people that will want to try it out with Wubi anyway, so here's a way to do it.

Disclaimer: I don't recommend the technique I describe here, but it works fine if that's what you want to do.

It involves downloading two ISOs, one for Xubuntu and another one supported by Wubi. I'll choose lubuntu since it's the smallest.

1. Dowload the smallest supported ISO: lubuntu-12.10-desktop-i386.iso
2. Download xubuntu-12.10-desktop-amd64.iso (I want 64-bit, but you can use 32-bit too)
3. Check the xubuntu md5sum (Wubi will check lubuntu, but you need to check xubuntu).
4. Download wubi.exe for release 12.10
5. Make sure wubi.exe and the lubuntu ISO are in the same folder. Run Wubi and select lubuntu. 
6. When it tells you to reboot, select "Reboot later".
7. Replace C:\ubuntu\install\installation.iso with the Xubuntu ISO (renaming to installation.iso)
8. Mount the Xubuntu ISO and copy initrd.lz and vmlinuz from the /casper/ directory over the one in C:\ubuntu\install
9. Edit the preseed.cfg file in C:\ubuntu\install\custom-installation\ so that it installs xubuntu-desktop instead of lubuntu-desktop
10. Reboot the computer
11. Select Lubuntu
12. Watch Xubuntu install
13. Reboot, select Lubuntu and boot into your new Xubuntu install.

You don't strictly need to predownload the lubuntu ISO but it's faster than letting Wubi do it. If you decide to use the Ubuntu ISO instead of lubuntu you do have to download the ISO beforehand (because Ubuntu defaults to the preinstalled diskimage and that won't work with this technique).

Notes:
I used the C: drive for clarity - if you install to a different drive then modify as required.
If it bugs you, you can rename the Lubuntu menu entry to Xubuntu using bcdedit or easyBCD. 

Here are some screenshots for selected steps:



Step 3: Check Xubuntu MD5 sum




Step 5: Run wubi.exe with lubuntu in the same folder



Step 6: Select to reboot later




Step 7a: Delete the existing installation.iso




Step 7b: copy the Xubuntu ISO and rename to installation.iso




Step 8: Mount the xubuntu ISO and copy vmlinuz and initrd.lz







Step 9: Set it to install xubuntu-desktop




Step 11: Select Lubuntu




Step 12: Watch it install Xubuntu

Credit: I got this tip from here ironically to install lubuntu prior to it being supported by Wubi.

Update:
The original post had this line: "This technique will also likely work with other unsupported flavours e.g. ubuntu-studio". It does with one caveat. Ubuntu Studio doesn't include the package required by grub to generate the menu entries that can boot a loop mounted install (lupin-support). So it will install, but you have to manually boot it the first time from the grub prompt and then install lupin-support.

 Here's how to manually boot any Wubi install:

search -s -f -n /ubuntu/disks/root.disk
probe --set=diskuuid -u $root
loopback loop0 /ubuntu/disks/root.disk
set root=(loop0)
linux /vmlinuz root=UUID=$diskuuid loop=/ubuntu/disks/root.disk ro quiet splash
initrd /initrd.img
boot