I can't find the vCLI where I expect it: vSphere > Downloads > Drivers and Tools
The vCLI installation package can be found here:
https://my.vmware.com/group/vmware/details?downloadGroup=VCLI600&productId=491
This is vCLI 6.0, but it will work with 5.x hosts as well.
In addition to the link above, you may want to bookmark VMware Developer Resources - VMware Developer Center for this (and other) downloads.
André