Create a portable persistent Linux Mint install on ext4?

[mihneachange]

Hello, been using Linux Mint on my computer since 2008 and been loving it. Now I want to take it a step further and make either a normal portable install or a live persistent install of Linux Mint on an external USB hard-drive formatted as ext4 .
I've already tried the following solutions, but came to some important road blocks:
1) a LiveCD ~ doesn't have persistence;
2) a FAT32 formatted LiveUSB ~ the Linux Mint files can be corrupted by Windows viruses, if I have to plug it into a running Windows machine;
3) normal install on an external USB hard-drive formatted as ext4 ~ it's not portable, since it failes to boot on any other computers besides the computer it's been installed on (boots only on my computer, that is);
4) live persistent install on an external USB hard-drive formatted as ext4 ~ it's not bootable (not even if before I install I set the ext4 file system permissions to allow full read/write/execute privileges for anyone).

Any ideas on how I could get a normal install on an external USB hard-drive formatted as ext4 to be portable?
OR
Any ideas on how I could get a live persistent install on an external USB hard-drive formatted as ext4 to be bootable?

[xenopeek]

Just boot from a Linux Mint installation ISO, attach your external hard disk and start the installer. Choose to do "something else" on the installation type question (choose "manual" if using KDE). Select to Install to the external hard disk (probably /dev/sdc but check to make sure), create a new partition table and then create the partitions you want (an ext4 partition mounted to /, and probably a swap partition), and make also sure you select to install the boot loader to the same device.

That might be a bit scary at first. Some have previously given advice to do this with your internal hard disk disconnected, so you can not mistakenly overwrite that.

[mihneachange]

I've already tried that and unfortunately the install is not portable.

It was point 3 of my original post: "3) normal install on an external USB hard-drive formatted as ext4 ~ it's not portable, since it failes to boot on any other computers besides the computer it's been installed on (boots only on my computer, that is);"

I'll also note that every time I installed to my external drive I have disconnected my internal drive so as not to mess up Windows.

Any other possible workarounds?

[usbtux]

normal install on an external USB hard-drive formatted as ext4 ~ it's not portable, since it failes to boot on any other computers besides the computer it's been installed on (boots only on my computer, that is);[/b]"

I'll also note that every time I installed to my external drive I have disconnected my internal drive so as not to mess up Windows.

http://youtu.be/gVCfeFOxGLQ External install (external hdd or to a flash drive 8G min nowadays)

Doesn't mater what format the drive to the computer. It should work on nearly any computer, the main problems you run into are video driver issues sometimes. So not install other video driver. You should install a 32bit as its far more portable ie 32 bit will work on 32 or 64 bit machines but 64bit wont work on 32.

You dont need to remove the windows drive at all - its just your present level of understanding on how to install.