I took a look at the ELAN driver. It doesn't appear to be complete.
According the document each command is 5 HEX bytes long:
Byte 1: Sync Byte (This is always FF)
Byte 2: Device ID (needs to match the device id of the DVR 00-FF)
Byte 3: Code (from the chart)
Byte 4: Reserved (Always 00)
Byte 5: Checksum (Sum of Bytes 2-4)

So the command for SEQ for DVR address 1 could beone of the following:
FF 01 65 00 66
FF 31 65 00 96