To create your Porteus UEFI USB device please download this
Step 1) Boot into the latest Porteus v2.1 in fresh mode
Step 2) Plug in your USB device
Step 3) Run the script AS ROOT: sh /path/to/create-efi-usb.sh
The result will be a UEFI bootable Porteus USB device. It will use the latest stable kernel compiled for EFI stub support.
I will write up a HOWTO for people that want to follow the procedure involved. The following HOWTO will include how to install Porteus to the hard drive and allow secure boot to load it on UEFI machines.
Please let me know how the process goes.
NOTE: The script will only run on a Porteus fresh mode (or save mode) install. It will download around 20Mb of files to install to your chosen USB device. The script does not mess with your UEFI firmware in any way. It also does not search any internal drive so to dual boot into windows from this USB you will need to modify refind.conf and add the word 'external' to line so it looks like this:
After this your windows install may be detected and you may be able to boot into it.