If you are bridging to the VM, assign it a.b.c.d/26 and don't assign it subnet mask 255.255.255.255. If you are routing to the VM, assign a.b.c.d/32 as an alias to the loopback interface and route a.b.c.d to its (unrelated, can be private) ethernet address.
Their comments seem to suggest you should be routing these IPs to your VMs. So assign these IPs as aliases to the loopback interfaces (since they aren't associated with any particular physical interface) and route them to them.
If you don't understand how to route an IP address to a machine, then you're out of your depth and should employ someone who does to work with your provider to get the configuration right.