I want to install Ubuntu Mini Remix but...

Ubuntu Mini Remix can't be installed "as is", for a simple reason, there's no installation software bundled with minibuntu.

You could install it by hand but I don't think it's an easy task.

Remember that Ubuntu Mini Remix wasn't create to be used "as is" but as a base you creating your own ubuntu based livecd.

In your remastered Ubuntu Mini Remix you'll add the software you want and, if you need it, an installer system.

** UPDATE FROM Nicolás Pierini **

I needed a CLI system for a very old PC (IDE HDD, so I use a USB disk)
that only has to run motion. I downloaded the mini-remix and started to
try after a lot of time found a solution..
It can be done in five steps:

1- Mount the fs

sudo mount -t squashfs -o loop filesystem.squashfs /mnt

2- Copy the whole squashfs to the hard drive (mounted in /media/hdd in
this case)

sudo cp -R /mnt/* /media/hdd

3- Copy the grub dir from a fresh installation of ubuntu (same version
as ubuntu-mini-remix. disk mounted in /media/newUbuntu)

sudo cp -R /media/newUbuntu/boot/grub/* /media/hdd/boot/grub

4- Open grub.cfg and repleace the UUIDs with the UUID of the hdd disk
5- Erase root password and let users login without password

sudo gedit /media/hdd/etc/shadow

repleace "root:*:14892:0:99999:7:::" with "root::14892:0:99999:7:::"

sudo gedit /etc/pam.d/common-auth

repleace "nullok_secure" with "nullok"

6- Finished. Now you can boot the PC from the ubuntu-mini-remix (hdd,
not liveCD) disk and add new users, or login as root.