Hi Adam,
Using Taskers HTTP POSTserver:port = https://api.pushbullet.com/api/pushes //the port is not needed unless requested by PushBullet, I didn't see it.
skip down to Data/File and enter each parameter on it's own line within the data/File box.
device_iden = IDEN //your IDEN # according to PushBullet, the device this push is to be routed to
under the line device_iden=YourDeviceIDEN // I would not have any spaces
enter type=note or whatever is the type
then on a new line enter
title=thetitle
then on a new line enter
body=the text of the message //don't know about spaces needing to be replaced by +'s or %20's
follow the formats below for the different types, note, link, address, list, file, etc.
if type = note
title = The title of the note
body = The note's body
if type = link
title = The title of the page linked to
url = The link url
if type = address
name = The name of the place at the address
address = The full address or Google Maps query
if type = list
title = The title of the list
items = The list items
if type = file
file = The file to push
type = The type of push this is
Not sure about the Content Type, but PB is expecting that in the data.
I copied some of this from the PushBullet site. They had typical code snippets, but nothing to tell you how to use them in tasker, and why would they.
Hope this gets you going in the right direction.
CazMaz