I came across this on the manasa-taramgini blog.

http://manasataramgini.wordpress.com...a-vaishnavism/

Most interestingly the sanatkumAra saMhitA gives two forms of upanayanaM, the vedic form for dvijas and tantric agnimukhaM version for women and shUdras. On recieving that they may perform several rites, but the pA~ncharatric brahmin is still supposed to perform vaidika rites to various deities in addition to the internal pA~ncharatric sacrifices to vedic deities given in the rudra rAtra.
Does anyone have more information on this?