1. Such a field modification needs to be approved by the manufacturer & performed by an authorized representative (typically a dealer).
2. Lift eyes & /or points are most commonly installed as a "factory installed" option for P/L reasons.
3. In 41 year+ spent in the lift industry can't recall seeing lifting points called out in a manual - unless it was for a special units designed for stevedore operations & or military use (typically the Navy). Used to write manuals (operators, parts, service / maintenance manuals).