Description & Instructions from retrosystemsrevival.blogspot.com:
Normally, Windows 9x cannot contain files larger than 4gb due to its file system limitation of FAT32. But, Windows 9x (95/98/ME) can use large files above 4gb with rloew's patch. This approach has a smaller set of files appear as a single file, but nevertheless does its job well.

Features:
**Use files larger than 4gb on Windows  95/98/ME
**Emulation of large files for Windows 95/98/ME
**Allows Programs to create files larger than 4GiB
**All large files intact on the Windows 9x platform
**Compatible with all programs
**Enjoy Blue-Ray video on Windows 9x

Requirements:
Windows 95/98/ME

Instructions:
1) Place the FILE64.DLL and FILE64.VXD files in your C:\WINDOWS\SYSTEM Folder.
2) Go to C:\WINDOWS\SYSTEM.INI (be sure Windows folder options allows you to see hidden files).

In the [386Enh] Section add the following line:
device=FILE64.VXD


Save the File.

3) Reboot your Computer.

Important:
Since the Large File Emulator is not fully compatible with normal file usage, the Emulator is designed to limit itself to specific Directories. To enable the Emulator for a new Directory, either Name it to "##64" or one of it's Parent Directores, such as C:\DOWNLOAD\##64\VIDEO.

Notes:
**The file emulator does not effect DOS Box. To properly move larger files requires rloew's XFILE Version 2.0 or later.
**Limitations included in files.
**The Unicode version is also included in the download. To install, simply boot Windows in safe mode and replace the existing files in the system folder with the Unicode files.