As MacOS X starting from 10.4 does not support AFP over AppleTalk any longer (and older versions also dropped support for some protocol versions), it is not possible to mount GlobalTalk shares using MacOS X 10.4 or newer.
It is possible to enable AppleTalk in the network preferences and also see the zones and servers in Finder, but mounting them will only result in an error message.

But there is a workaround:
The program "ShareWay IP Pro" can act as a gateway server. It can be found here in Macintosh Garden (DL #5). But there is no serial number to register it yet...

This program can now be started on a machinr running MacOS 7.5-9.2 and has to have TCP/IP and AppleTalk enabled.
Then, servery (eg. from GlobalTalk) have to be added manually to the list of servers and each server needs its own port (on the machine running ShareWay IP).

I've tried it with a single GlobalTalk server on the default port.

Now, on a machine running MacOS X 10.4.11, in Finder under Network > My Network (not the AppleTalk zones!), the selected server appears and can be mounted (using AFP over TCP/IP).
It is really really slow, much slower than on a classic machine via AppleTalk - but it is working.

I have not done further tests due to its lack of speed, but it is possible to use it.