Use a dist like Ubuntu or Mint (only ones I have experience with) that ships with the HPFS module, others may also include it but lots don't, though it can probably be installed on most. Plug the USB/IDE drive in, click the partition to mount it (might be automatic) and drag and drop or otherwise copy the files seems the simplest. Even better if his computer has an IDE interface.
EAs will be lost, which shouldn't matter for data.
The Linux HPFS support is pretty good, it'll even handle our libc symlinks and permissions if @UNIXROOT for example was on a HPFS partition and will copy EAs to another HPFS partition though it can't actually use the EAs.
Linux handles our JFS pretty good too, but it does get confused by the lack of permissions and you need to be root or use sudo. I noticed that Mint even mounts my OS/2 JFS as case insensitive now to avoid the problem of having FOO and foo on an OS/2 partition.