It is well-known that Shiva's son Ganesha is the general of Shiva's army of Ganas. What's not as well-known, however, is that Vishnu also has an army, led by the god Vishvaksena. Vishvaksena plays an important role in the Sri Vaishnava sect; as I discuss here, Vishvaksena learnt the all-important Dvaya mantra from Lakshmi and taught it to the Vaishnava poet-saint Nammalwar. And as I discuss in this question, Nammalwar is himself considered an incarnation of Vishvaksena.
But my question is, what scriptures discuss the story of Vishvaksena? No doubt he's discussed in the Pancharatra texts (which I discuss here), but what other scriptures describe him? There's a reference in a few Puranas to Shiva's incarnation, Kalabhairava, (temporarily) killing Vishvaksena, but those are likely interpolations. The Srimad Bhagavatam mentions him as one of Vishnu's attendants, but are there any scriptures that describe the story of his birth and the like?
The story I could find is the one told in this PDF, which is a compilation of extracts from different Puranas which describe the story of Venkateshwara (the Vishnu deity in Tirupati, aka Balaji or Srinivasa). In particular, it gives a story from the Vamana Purana. In this account, the Apsara Kuntala is cursed by the sage Durvasa to be born as a human being. She takes birth as Suvarchala, daughter of a cruel man named Virabahu. Suvarchala then has a child with Varuna: the ocean god named Vishvaksena. When Vishvaksena grows up, he goes to the Tirumala hills in Tirupati and engages in Tapasya, whereupon Vishnu appears before him and appoints him as the general of his army:
Kuntala was reborn as a daughter to Virabahu, a cruel personality. She was named as Suvarchala. She made her parents very happy while growing up. She became very famous for her beauty and good character. Virabahu performed her marriage ceremony with Bhadra who was the son of Dharma.
One day in the Phalguna month, sukla paksha, she finished her bath in the river Narmada and stood near the mountain. Varuna deva saw her beauty and was very much impressed and asked her to wish for a boon. Suvarchala asked him to bless her with a good son which he readily granted. Suvarachala felt very happy.
After some time, Suvarchala gave birth to a beautiful baby boy. When he was born, the auspicious signs like the sound of celestial drums was heard, flowers rained from the sky, and the breeze blew with fragrance. The baby’s face was shining like a full moon, with lotus eyes, his skin was like pure gold and his feet had the impressions of conch, chakra and the mace. He was born in the star of Pushya. He was growing like a moon in the sukla paksha with valor. When the boy reached his tenth year, Suvarchala passed away. His father also left him.
The boy became an orphan and started wandering in the surroundings of the kashyapa ashramam. Sage Kashyapa grasped that this boy was from the royal family and the son of Varuna. He accepted the boy as his student (Sishya). Kashyapa gave the upadesam of Gayathri mantra and taught him all the Vedas along with Siksha and Vyakaranam. After the completion of his education, the boy sought permission from sage Kashyapa to do penance. Kashyapa allowed him with blessings.
The boy went to Vrushadri and started rigorous penance with austeries. Lord Srimannarayana appeared in front of him and blessed him with the boon of becoming the army chief of Lord Srimannarayana. He was also blessed with a divine form similar to Lord Narayana (sarupyam) having sankha, chakra and gada in his hands.
The PDF says this story is from "Kshetra Khanda, Chapter 23" of the Vamana Purana. But at least in the table of contents here, the Vamana Purana doesn't seem to be divided into Khandas. So can anyone point me to the relevant chapter of the Vamana Purana?
Are there any other scriptures that describe this story of Vishvaksena being the son of Varuna and Suvarchala? Also, who is Suvarchala's father Virabahu? If possible I would like to trace back the ancestry of Vishvaksena as far as I can.