You can run HS4.x on ANY hardware with x86 CPU. Just install a 32-bit linux like CentOS 5 (easier than 6 or 7) or debian or similar.
Install python and some other prerequisits …
It is the same as running a VM.
you can’t update firmware via expert. You always have to patch it manualy and hope it is still running.
If you want to run the original diskimages (not only binaries, also the unix kernel…) you have to use a mainboard which is 100% compatible with the original. That is because HS runs a very down-trimmed unix kernel which makes it small and stable – but also only supporting exactly one chipset and exactly one network card.
Once you have a near-original HS4 it is also firmware upgradeable like the original.