shrImAtre namaH
Like there are samskAras such as garbhAdhAna etc. for the aihika sharIra, dahana and other samskAras have been prescribed for the AmuShmika sharIra as well. My familiarity in this subject is mainly regarding AshwalAyanIya aurdhwadehika prayoga. Works like brahma karma samucchaya describe these in greater detail. Apart from swashAkhA, influence of deshAchAra also seems to be an affecting factor in this regard. The encyclopedic vaidyanAtha dIkShitIya, as always, serves as the chief source of information on this subject as well.
When a dvija knows that he is approaching his last, he should perform Achamana, wear pavitra, perform prANAyAma, perform a sankalpa for godAna and invite five brAhmaNas to offer godAna. The five-fold godAna involves the dAna of pApa dhenu for destruction of sins, utkrAnti dhenu for sukhotkramaNa of the prANa, vaitaraNI dhenu for crossing over the vaitaraNI river, RNa dhenu for absolving the RNas or debts from previous seven births and mokSha dhenu for attaining salvation. This is followed by dasha dAna-s, involving the dAna of dhenu, bhUmi, hiraNya, tila, Ajya, vastra, dhAnya, guDa, rajata and lavaNa [cow, land, gold, til, clarified butter, clothing, grains, jiggery, silver and salt]. For the jIva to get rid of darkness and thirst in uRdhwa lokas, jala and dIpa dAnas are also performed.
Then, while resting his head on the lap of his son, with his head towards the south, sUktas should be recited. For those incapable of reciting the same, son or his representative should recite the sUktas in the right ear of the departing person. The primary sUkta recited here is the nAnAnAmiti sUkta from the ninth maNDala of Rgveda, consisting of twenty-two hymns. puruSha sUkta, upaniShad, bhAgavata, gItA, viShNu sahasranAma etc. are also recited. While reciting bhagavannAma, gangA, tuLasI and sAlagrAma tIrtha should be poured into the mouth of the departing person, till prANotkramaNa. Shamkha nAda should be made to fall on the ears of the departing person. If conscious, the departing person should recite bhagavannAma or upadiShTa mantra but not shuddha praNava like popular belief, for which everyone is not eligible. A shrIvidyopAsaka, especially a pUrNa dIkShita, has additional instructions based on guru sampradAya and Tantra pramANa, which need to be learnt from Sadguru.
kAmeshwarI chApi katham na sA tvam
niShkAmamantaH kuruShe kShaNena |
bhaktasya siktasya parAtmabodha-
pIyUShadhArAnikareNa devi ||
guptajnAnamaNiM vimohamakaraM rAgoragairdustaram
tR^iShNApeyachala~nchalaM parivaladdurlobhakUrmAkulam |
samsArAbdhimimaM taretsuviShamaM sAhAyyahInaH katham
dInastadyadi na tvamAtmakR^ipayA santAriNI tAriNI ||