You may be interested in the open-vm-tools project:
I compiled these tools in other environments, and I expect it would be possible to compile them for Zeroshell. However, it may not be easy, and I do not have the resources to carry that banner. In the short term, it should be possible to compile the vmxnet driver for the kernel which Zeroshell uses. This is really the only aspect of the tools that Zeroshell would utilize. In my case, I compiled the vmxnet module for RHEL 4.4 in order to put it on a kickstart disc for network installations via http within a VM. Using just the driver gave me the performance I needed.