How can I setup my HP DAT24 internal tape under HP-UX 10.20?

[xujun]

I have two tapes ,one is external,the other is internal.
The kernel has include cs80 and stape drivers, the external one ARCHIVE VIPER 150 ,SUN tape can be detected correctly.
This is the output of ioscan :
Class I H/W Path Driver S/W State H/W Type Description
=======================================================================
tape 0 10/0/15/0.4.0 stape CLAIMED DEVICE ARCHIVE VIPER 150 21531
/dev/rmt/0m /dev/rmt/c2t4d0BEST
/dev/rmt/0mb /dev/rmt/c2t4d0BESTb
/dev/rmt/0mn /dev/rmt/c2t4d0BESTn
/dev/rmt/0mnb /dev/rmt/c2t4d0BESTnb

but it is so old, the capacity is limited. The internal HP DAT24 tape still can be detected. The SCSI ID is default value as 3.

I have tried to use command as following:
mknod /dev/scsi/3 c 205 0x003000
or
mksf -C tape -I 0 /dev/rmt/tapename

How can I choose instance number and LUN correctly?

By the way, how to use the tools called mtx provided by HP TAPE driver CDROM ?

What can I do now ?
Best Regards.

xujun