Yes you can.

Simply add to the Settings of the event as much information as you can.

If the venue is not yet fixed, enter whatever information you can as concerns the location (country, city) and return at a later point to add the venue information once it is known.

If the venue (= building) is not listed in the system, contact Indico.UN user support

Without a Short title (for badge) and a contact email or telephone number, registration cannot be opened. These are the required elements.