A new VMware Fling was release a few weeks ago and I missed it. You can now install VMware tools in your nested ESXi Hosts. It works with nested ESXi running 5.0, 5.1 or 5.5. I’m running 5.1u1 (1312873) with nested 5.1u1 for this post and it works great. I suppose this works with VMWare Workstation 10 but I haven’t tried it.

The Fling, or tools can be downloaded here.
http://labs.vmware.com/flings/vmware-tools-for-nested-esxi

Steps:

1) Login to the ESXi console and enable SSH or the ESXi Shell.
a) In vCenter, open a console on the nested ESXi VM.
b) Press F2 and login as root.
c) Scroll down to Troubleshooting Options and press Enter.
d) Select either Enable SSH (prefered) or Enable ESXi Shell and press Enter to enable.
e) If SSH, launch Putty or an Xterm and login as root. If ESXi Shell, press ALT+F1 and login as root at the console. Press ALT+F2 to get back to the ESXi DCUI.

2) Whether you logged into the Host with SSH or at the console, place the ESXi Host in maintenance mode.
> esxcli system maintenanceMode set -e true

Now, verify Maintenence Mode is enabled.
> esxcli system maintenanceMode get
Enabled

3) Launch vSphere Client and connect directly to the nested ESXi host as root.
a) On the Configuration tab , select Storage. Right-click the local datastore and select Browse datastore.
b) Click the Upload A File icon and select the esx-tools-for-esxi-9.7.0-0.0.00000.i386.vib file and click Open.
c) When done, close out of the vSphere client session.

4) Back in the ESXi Host, change to the volume (datastore) where you placed the VIB.
> cd /vmfs/volumes/<your local datastore name>
> ls -l esx-tools*  (to verify that the file is there)
> esxcli software vib install -v /vmfs/volumes/<your local datastore name>/esx-tools-for-esxi-9.7.0-0.0.00000.i386.vib -f

Installation Result
Message: The update completed successfully, but the system needs to be rebooted for the changes to be effective.
Reboot Required: true
VIBs Installed: VMware_bootbank_esx-tools-for-esxi_9.7.0-0.0.00000
VIBs Removed:
VIBs Skipped:

5) Reboot the Host and set the reason for the reboot action.
> esxcli system shutdown reboot -r “Hey, I just installed VMware Tools on nested ESXi”

6) In vCenter (Web or vSphere client), check the Summary page for the nested ESXi Host. Is should now show VMware tools installed and current. Reference images are shown below.

a) Before VMware tools (showing both Web and vSphere Client images):

b) And after VMware tools (showing both Web and vSphere Client images):