On a 3Com SuperStack 3300 this is referred to as "roving analysis".
See http://support.3com.com/infodeli/tools/switches/ss3/management/ug/dua1695-0baa05.pdf, search for "roving analysis" (page 86).
It does not appear to support monitoring multiple source ports ("monitor port") with a single destination port ("analysis port"). So capturing *all* traffic on the switch with a single analysis port would not be possible. You're also not able to select a trunk port as a monitor port, or select an entire VLAN as a source.
As mentioned by Bill Stackpole, to monitor more than traffic to/from a single host on a single port on that switch, you'd need to monitor a port on another switch that is part of the backbone supporting that switch. What you need to do is figure out the path that the network traffic you want to monitor will take, and then monitor at that location. For example, suppose you have a setup...
[Hosts A,B,C,D] - [Ports 1/1-4 : SuperStack 3300 : Port 1/5] - [firewall] - [Internet]
...and you wanted to monitor all traffic between Hosts A,B,C,D and the Internet. Then you would use port 1/5 as your monitor port.
Given the capabilities of this switch, in no case will you be able to monitor at once all traffic passing through the entire switch. You'd need to swap out the switch for one that supported multiple ports or VLANs as the monitor source, or a hub.
Greg S.
