Can you use cURL, REST or some method to script file upload?

Can you use cURL, REST or some method to script file upload?

I am migrating some applications from Dabble to Zoho Creator and the migration tool only migrates the text data, not the attachments. I tried using cURL and a public version of the form I created to POST data to the application, but I could not get that to work due to there being javascript and several other forms on the same public form page.

I tried the REST API but again could not upload files.

Is there any way to script the uploading of files? My client has thousands of attachments and they can't be uploaded manually.

Thanks,
Gillian