The simple answer is: "yes, of course." If you're using Plone > 3.1, you do it pretty much the same way you set up a cluster in Plone 4 or 5.
Will it solve your problem? If your problem is that you're not making good use of all the cores on a multi-core machine, a zeocluster is a good way to solve it. The threading in a single Zope instance is very inefficient. A cluster does much better.
At the same time, you should look to see if you can reduce the work done by your Zope instances. Having a proxy cache and a good caching setup is the key.
And, spend some time updating to Plone 4.x. It's faster out-of-the-box at rendering pages and has a much more efficient blob-handling system. You'll also find that the documentation for Plone 4.x is excellent, including that on scaling. If you can't do that, track down a copy of "Practical Plone 3" for documentation on cluster architecture and caching.