We have this software that has a webservices component.
Now, the administrator of this system has come to me, wanting to import data into the system by using the webs
You can't PUT using an HTML form (the spec defines only GET/POST for forms).
However any HTTP API should allow you to PUT, in the same way that it allows you to GET or POST. For example, here's the Java HTTPClient documentation, which details PUT alongside all the other HTTP verbs.
I don't know which language you're using, but I think it's going to be pretty trivial to write an app to perform an HTTP PUT.