Bernardo,
I have two VFP code samples (membership required) on my web site:
Using Change Notification Objects to monitor changes to the printer or print serverhttp://www.news2news.com/vfp/?example=485Simple printer queue monitor: deletes, pauses, resumes print jobs for local printerhttp://www.news2news.com/vfp/?example=373They may give you an idea of what can be achieved (at least) with Windows API calls.
The first code sample works in blocking mode. It allows to obtain the name of the printer, the name of the machine that created the job, the number of pages to be printed and already printed, the size of the job in bytes and more.
Also check WMI objects:
http://www.news2news.com/vfp/?example=368&ver=wmi