Hi,
To convert Hyper-V VMs to ESXi you will need to covert them "as physical machines". For this you need to power on the VMs and provide the IP address of these VMs. They will be treated as physical machines for conversion.
Also note that our last GA release of stand-alone converter does not support Windows 2008. So you will need to use converter built into WS 6.5 OR converter built into VC 2.5 (update 2). Unfortunately, there is no way to achieve what you are trying to do with stand-alone converter 3.0.3.