If you don’t know what a cmdlet is looking for, the first place to look is Get-Help:
Get-Help Set-ADUser -Full
You would see…
-Replace [hashtable];
Required? false
Position? Named
Accept pipeline input? false
Parameter set name Identity
Aliases None
Dynamic? true
On the question of is it possible, yes it is. You need to use Get-ADUser to get the attributes, format them (e.g. comma separated, semi-colon, separate lines), and then use Set-ADUser to set the info attribute: