Yes, you can certainly do this. Simply convert the file to hexadecimal format (using whichever language is appropriate in your case) and then publish that hexadecimal data as a stream item.
If your file is very large, you may want to look at using the binary cache feature in MultiChain (alphas), which allows you to pipe data directly into MultiChain directly via the file system. See section 5 of the 'Getting Started' guide for an example:
https://www.multichain.com/getting-started/