Doesn't look like you can change via the interface. You can use the following to add a 2 minute option.
Declare @ModuleDefID Int
select @ModuleDefID = ModuleDefID from {databaseOwner}[{objectQualifier}ModuleDefinitions] where FriendlyName = 'Events'
INSERT INTO {databaseOwner}[{objectQualifier}Lists] (ListName, Value, Text, ParentID, [Level], SortOrder, DefinitionID, Description, PortalID, SystemList, CreatedByUserID, CreatedOnDate, LastModifiedByUserID,
LastModifiedOnDate)
VALUES ('TimeInterval','2','2',0,0,1,@ModuleDefID,'',0,0,-1,getutcdate(),-1,GETUTCDATE())
GO
Cheers
Roger