Got finally sick of opening the vSphere client every time I needed access to a virtual machine running on my ESXi 4.1 server. Did some googling and trying out couple of options and finally found a way to do this.

“C:\Program Files\VMWare\Infrastructure\Virtual Infrastructure Client\4.1\vmware-vmrc.exe” -h <esxi_host> -u <username> -p <password> “[datastore1] myvm/myvm.vmx”

via Direct shortcut for opening a console to VMWare ESXi 4.x virtual machine « Man-in-the-middle.