I couldn’t find a step-by-step how to, so here goes:

My new Dell R710 has 4 on-board Broadcom NICs, and an add-on Intel Quad Port NIC.  After installing ESXi 4 Update 1 (customized ISO for Dell) I saw the Broadcoms, but not Intels.  The solution is a driver CD that is available from VMWare, but the installation process is a couple of hoops.

- Download the CLI (command line interface) and the drivers you are looking to install:

http://downloads.vmware.com/d/info/datacenter_downloads/vmware_vsphere_4/4#drivers_tools

I download the VMWare vSphere CLI 4.0 U1   (I ran it from Windows 7 64bit).  It is under the ‘Drivers and Tools” tab,  ”Automation Tools and SDK” branch.  I also needed the “VMware ESX/ESXi 4.0 Driver CD for Intel 82575 and 82576 Gigabit Ethernet Controller”, which was also under the “Drivers and Tools” tab, within the “Driver CDs” branch.

2 – Install the CLI tool (on Windows)

3 – You will need to burn the driver ISO to CD and put it in the drive of the same machine where the CLI tool is installed (or mount the ISO on that machine).

4 – In Windows, Start – All Programs – VMWare – VMWare vSphere CLI.  This will open a familiar looking Windows command prompt window.  You should default into the installation directory of the CLI tool

5 – type “cd bin” then press Enter in that command prompt window

C:\Program Files (x86)\VMware\VMware vSphere CLI>cd bin

6 – type “d:” then press Enter (assuming d: is the drive where your driver CD in mounted)

C:\Program Files (x86)\VMware\VMware vSphere CLI\bin>d:

7 – type “cd\offline-bundle”
8 – type “dir”.  You will need to figure out what file is your driver file.  For me, it was “INT-intel-lad-ddk-igb-1.3.19.12.1-offline_bundle-185976.zip”
9 – then type the command to install the drivers:
D:\offline-bundle>c:vihostupdate.pl –server 10.5.100.101 –install –bundle INT-intel-lad-ddk-igb-1.3.19.12.1-offline_bundle-185976.zip
This command connects to ESXi server 10.5.100.101 to install the Intel NIC drivers.  Substitue the IP address of the server you want to update.  You will be prompted for a login and password, and the server will be put into maintenance mode, and rebooted at the end – so MAKE SURE you have no running VMs on this system.
You will see something like this:
Enter username: root
Enter password:*********************
Please wait patch installation is in progress …
The update completed successfully, but the system needs to be rebooted for the changes to be effective.