Since I was unable to find any documentation concerning the XML-RPC endpoints for the new Nessus server, I ran it through Tamper Data and here's what I got (not everything, but a good chunk)

[code lang="php"]

URL=https://172.16.1.175:8834/login
POSTDATA =seq=1505&password=MyPassword&login=tim

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/plugins/list

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/report/list

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/policy/list

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/plugins/preferences

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/preferences/list

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/policy/add
POSTDATA =plugin%5Fselection%2Efamily%2EWindows%20%3A%20Microsoft%20Bulletins=enabled&Global%20variable%20settings%5Bfile%5D%3ASSL%20key%20to%20use%20%3A=

[/code]

Basically it's just everything you'd read from the XML file url-encoded and send in one gigantic post

[code lang="php"]

URL=https://172.16.1.175:8834/scan/list

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/scan/new

POSTDATA =seq=2145&target=172%2E16%2E1%2E101&scan%5Fname=265&policy%5Fid=1

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/scan/pause

POSTDATA =seq=3587&scan%5Fuuid=3b98722d%2Df5ec%2Da565%2D7a7e%2D88335e45a5a139828ae33ca3eed1

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/scan/resume

POSTDATA =seq=9975&scan%5Fuuid=3b98722d%2Df5ec%2Da565%2D7a7e%2D88335e45a5a139828ae33ca3eed1

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/report/hosts

POSTDATA =report=3b98722d%2Df5ec%2Da565%2D7a7e%2D88335e45a5a139828ae33ca3eed1&seq=5458

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/report/tags

ditto

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/report/ports

ditto

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/users/list

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/users/edit

POSTDATA =seq=3802&admin=1&login=tim

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/report/hosts

POSTDATA =report=3b98722d%2Df5ec%2Da565%2D7a7e%2D88335e45a5a139828ae33ca3eed1&filter%2E0%2Efilter=plugin%5Fid&seq=7176&filter%2E0%2Evalue=10011&filter%2E0%2Equality=equal%2Dto

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/report/tags

POSTDATA =report=3b98722d%2Df5ec%2Da565%2D7a7e%2D88335e45a5a139828ae33ca3eed1&hostname=172%2E16%2E1%2E101&seq=5498

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/report/details

POSTDATA =report=3b98722d%2Df5ec%2Da565%2D7a7e%2D88335e45a5a139828ae33ca3eed1&protocol=tcp&hostname=172%2E16%2E1%2E101&seq=3380&port=445

[/code]

[code lang="php"]

URL=https://172.16.1.175:8834/report/delete

POSTDATA =report=3b98722d%2Df5ec%2Da565%2D7a7e%2D88335e45a5a139828ae33ca3eed1&seq=4148

[/code]

It's unclear whether or not you can download and upload scan results using a home feed; probably not, and thus Tenable face palms itself yet again.