From the Manual of Indulgences:
For those who cannot go to church or the seriously ill
In addition, sailors working on the vast expanse of the sea; the countless brothers and sisters, whom the disasters of war, political events, local violence and other such causes have been driven out of their homeland; the sick and those who nurse them; and all who for just cause cannot leave their homes or who carry out an activity for the community which cannot be postponed may obtain a plenary indulgence on Divine Mercy Sunday, if totally detesting any sin, as has been said before, and with the intention of fulfilling as soon as possible the three usual conditions, will recite the Our Father and the Creed before a devout image of Our Merciful Lord Jesus and, in addition, pray a devout invocation the the Merciful Lord Jesus (e.g. "Merciful Jesus, I trust in you).
If it is impossible that people do even this, on the same day they may obtain the plenary indulgence if with a spiritual intention they are united with those carrying out the prescribed practice for obtaining the indulgence in the usual way and offer to the Merciful Lord a prayer and the sufferings of their illness and the difficulties of their lives, with the resolution to accomplish as soon as possible the three conditions prescribed to obtain the plenary indulgence.
(The three conditions are sacramental confession, Eucharistic communion and prayer for the intentions of the Pope.)
Hope this helps!