No, none of the description in this guide applies to UEFI. The UEFI firmware loads its bootloader as a PE binary from a FAT filesystem, not a binary blob from sector 0, and the CPU is already in 32- or 64-bit mode. The interface for calling firmware routines is also completely different.
This is a decent equivalent guide for UEFI: http://www.rodsbooks.com/efi-programming/hello.html