We are trying to do this with Fixed Disks.
The problem is not being able to see results in an easy way. As you have to go through each node one by one - lots of work for big companies.
Oh how I pray that one day SolarWinds manages disk discovery automatically. Please God, please, I beg you heavenly Father Mother Supreme IT God in the Sky.
Depending on what you want to import, you may want to look at what the "Define monitoring settings" has to offer. In there you can tell it to import only trunks, or add filters of various sorts, the same as you would for a manual import. It isn't completely perfect, but it does work. The advanced filtering options allow you to drill in further, like my example here where an interface description or alias has the word open in it and I don't want to import that since I know for us it is generally an access port with a phone hanging off of it but no server or PC.