Is there any way to set display options (in the scene view) using Python? I couldn't find it in the docs.

I want to script a new attribute vector visualization in the scene view (easy not in a script).

hscript commands are available from Python, so this can be done with something like the following:
hou.hscript(“viewoptadd vector tu; viewoptset tu attrib(tangentu); viewoptenable * all +tu”)

works perfectly, thanks!