Transmitting Data over USB Port Intended for Flash Drive
Let me re-phrase your question. You have a device, which is acting as USB host, such that it can read and execute files if a USB flash drive is attached. So, your gadget is USB HOST.

If you have a regular desktop PC or regular laptop, they are also USB Hosts. Connecting host to host doesn't work in USB framework. So, you want your PC to act as USB DEVICE, to emulate the ordinary USB flash drive (aka "Mass Storage" device class).

In this situation no driver on PC side can turn the PC into device. To do so, your PC must have so-called OTG functionality (or "dual-role-data" port). Today almost every small-size gadget (like tablet or smartphones) do have this functionality, but not regular desktops. If it has OTG, when connected to another host using correct "OTG cable", these devices may look as the desired Mass Storage device, just as a USB flash drive or HDD enclosure. In this case you don't need to write any drivers to accomplish your goal of your device executing files from OTG PC. 

Unfortunately, these days the OTG tablets/phones stopped to pretend to be MSC devices, they are now supporting an extension called MTP - Media Transfer Protocol. This is an extra layer on the top of MSC, and not every older USB host supports MTP, and will be unable to see the media and automatically execute files.

So, you don't have many options. Either your PC must have the standard OTG functionality, or there should be a dedicated add-on PCI card that acts as USB device and provides access to your storage as USB MSC device. I know one PCI card that acts as device on a PC, but it is designed for USB test and certification purpose, and I am not sure if it is flexible enough to emulate USB mass storage device.

So your perspective is pretty dim, sorry.