Remember, it is an update, so Mac OS 8.5 or 8.5.1 would be needed to begin with.
You could install/copy the system and the update on/to an external Mac-formatted (Mac OS Extended = HFS+) SCSI hard drive or Mac-(re)formatted CompactFlash card in a PC Card adapter for CF connected to the PB 1400cs.
As you can see, the downloads are encoded MacBinary (.bin). As mentioned in an earlier reply, always keep the encoding intact until on the old Mac (PB 1400cs). Once there, use StuffIt Expander for the decoding. Drag the downloaded/transferred .bin files onto the StuffIt Expander program icon. Do not double-click on a .bin file that has been on a more modern computer (Mac or PC).
An smi file is a self-mounting image. In the case of multipart downloads, you would decode one .bin file containing the .smi and the other .bin files containing the parts. When decoded, place all these in one common folder. Double-click on the .smi to mount the entire image. If necessary, the entire mounted image can be copied to a Mac-formatted (Mac OS Extended = HFS+) hard disk or CompactFlash card.