NetBackup doesn't specifically care where the robot is found.
The question/issue is to get the host operating system to see the robot first.
For this you may need an appropriate driver for your host (robot control host).
For the SL8500 NetBackup won't have a control host as such. This type of library is configured as an ACS library, and it is controlled by a control station. NetBackup does not directly control the library is send request to the control station across the LAN, who then performs the required actions.
So it's not really a question if NetBackup supports SAN or not, its that the library is not designed to work like that.
If you have a SL8500 library, you should already have ACSLS running.
You can share a SL8500 between multiple hosts by implementing ACSLS volume access control
I have this robot, and we use the acsls. We found that our hosts were not able to push the tape drives and since they are locked during backups we were mulitplexing them which causes issues.
We ended up putting a device between the source systems and the SL8500 and are extremely happy with it.