Hi dude ...
Yes, company can appoint alternate director since it is provided in AoA.
Procedure is to convene Board Meeting and pass a resolution to appoint alternate director.
(However, don’t involve Sec. 257 over here since alternate director is going to be appointed in BoD meeting and not in GM.)
An individual who is already a director in another companies (assumed no. of other companies are in limit) can be appointed as alternate director.
No separate procedural impact will be there for Annual filing. Follow routine procedure.
Intention of not returning for 8 months is enough for appointment of alternate director.
Eagerly awaiting for other valuable views.