Sure, although using the PxPlus Apache or EzWeb server makes it a little easier.
With the PvxWeb server you have to parse the data out of the body received, whereas the PxPlus Apache or EzWeb provide the file contents directly.
Also Webster+ has an [upload] short code that makes file uploads even easier. Our Webster+ demo system actually shows doing this for images and data file downloads and uploads.
Basically when using Webster+ the system automatically places the uploaded file contents in a temporary file for you so all you need to do is rename/copy that file.
For example (from the demo site)
[upload imagefile$ size=20/4.5 event=uploader@product]Click or drag new image here to change[/upload][/color]
This short code will provide a file upload region that when clicked or has a file dropped on it, will place the file contents in a temporary file, puts that file name in the variable imagefile$, then fires the event "uploader@product" (i.e. run uploader passing it event "product").