1) if the physical machine is local to you then:
a: P2V (convert) the physical machine to a local ESX server.
b: copy the files from the local ESX data store to the remote data store. You can also copy these files to your desktop from the ESX data store then copy the files from your desktop to a remote site desktop, then copy from the remote site desktop to the remote esx data store.
2) if the physical machine is remote and you want to convert it to a esx host that is remote then you will need to install VM Converter on a remote workstation to run it.
The latency across a WAN will make vm converter fail unless you are pumping 100Mbps or more.
I have remote ESX servers connected to T1 lines (1.5Mbps) and I clone or P2V the machine needed locally then copy the VMDK files over to the remote data store via my desktop to a remote desktop then into the remote data store.
It works for me very quickly. I'm sure there are tons of ways to do it but this way works 100% without fail for me.
plus I can plan when I want to copy the files across the remote connection to reduce impact on the line.