The server my projects are currently required to use is a
shared host, with PHP upload file size and processing time limits
that make it impossible to work with files >500K.
Is there any way to build an upload system in Flex that can
allow users to work with files regardless of size? Everything I
have found in my searches of Flex resources all points to
server-side scripts to pass the upload target file to.
Regardless of size? Since your server has limitation on file
uploading, you have no way to work around on your flex client side.
The only way is to change the limitation on your server or check
the size of the files before uploading and return a warning for
users if any files too big.