4.6? No. -current is already beyond 4.6.
Your hardware is apparently ACPI-only. (APM does
not appear within your dmesg.)
OpenBSD will use either ACPI or APM if both exist on the hardware. The unused feature will appear in the dmesg as "not configured". An admin can disable ACPI or APM to force the use of one or the other if both are on the hardware.
ACPI development has been ongoing and active for years in OpenBSD. But it is not to the point where suspend/resume or suspend-to-disk is operative. No matter which hardware feature is available, the user interface on the OS is apm(8) and apmd(8).
The "howto" you referenced does not have specific instructions for your hardware model, nor for the release of the OS you're using.
The tphdisk "instructions" that are produced by running the program give an
example of configuring a FAT16 partition for use with the program. You appeared, in your first post, to have difficulty with this, due to the size of your partition. FAT16 is limited to 2GB. It is important to try to understand what the implications are of using a command that you see in instructions, or in a "howto". Blindy typing and hoping do not serve a responsible administrator well.