You can use the program VMware Converter: http://vmware.com/products/converter/
Converter will allow you to import virtual machines in a number of formats into ESX.
Or perhaps if you browse the datastore from the VI Client, is there a button for uploading files? (an up-arrow symbol)
As appk said, upload vmx and vmdk(s) files to esx. If they're in 2gb format, use vmkfstools to import as a solid file (the vmdk files). After that, place files in a folder on the vmfs filesystem. Next what i would do is edit with vi the vmx file, just to be sure that everithing is ok. And finally, with VIC, browse the datastore and register the vmx file!
You can use the Remote Command-Line Inteface (RCLI) for running certain commands on ESXi.
One of the commands that may be of interest to you is vifs which allows the upload/download of files.
The interface is available as an installable or as a virtual appliance. See the following link for more info:
You can also access a "linux like" console which is a bash shell utilizing busybox.
To access the console, go to the physical server, press Alt+F1, type unsupported (wont be displayed), and press Return.
You will then be prompted for the root password which will log you into the "console".
Logging into and using the console is not supported by VMware.
See the following KB for further information: http://kb.vmware.com/kb/1003677/