Basically, I want to create a USB that runs a code/executable I've specified in a text based environment from a flash drive. I have no idea if there's any distro I could tweak a bit, or if I have to create one on my own. I have some requirement for the distro/OS.
I need the OS to:

• Recognize Windows hard drives by the same device name (ex. ":F")
• Boot quickly
• Be USB bootable
• Have a configurable autoexec file

Thanks in advance!

Welcome to LinuxQuestions.

As you probably discovered linux does not know anything about drives nor drive letters.
Typically c: drive is the first partition on the boot drive where windows lives, d: most likely an optical drive, e and on would be other drive / partitions in the order they were created. It is also possible for one to change the drive assignments (excluding c:). So you may not be able to map the drives exactly unless you examine the registry.

You can mount the drives to any mount point desired but will still be accessed as e.x. /mnt/windows_drive_mount point. You can create an alias where by executing c: will change to the mount point.

What exactly do you want to configure in this "autoexec.bat" file. Depending on what you want to accomplish the equivalent might bash_profile or rc.local.

In general installing linux to a USB drive is no different then an internal drive.

In reality almost all modern linux could easily be made to boot from a usb and into a command line shell. It would be faster.

Since you say code, it may or may not be easy. Just what exactly do you want to perform?

To be precise, I want a bootable USB that directly renames sethc.exe in C:\Windows\System32\ on the the Windows hard drive that the USB is plugged in to. Therefore, the Linux OS needs to recognize the Windows hard drive and its name for it to be able to preform this act automatically during boot.

From my experience, Linux always had different names for different computers' hard drives. The drive was called something like:
"B0743G123U918L6K". I could therefore not create a script for this purpose.

Plan on forgetting your Windows password often?

Well...

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