I'd like to install a X mouse cursor theme like:

I have Lubuntu with lxappearance, but failed to find an appropriate package for this.
(Update: including more details after hunting down the old cursors)
The 'original' X cursors are certainly in the basic packages for X server or X client libraries. It is a font, technically.
(It is in the bitmap font /usr/share/fonts/X11/misc/cursor.pcf.gz in package xfonts-base)
So there is no such package to install these old cursors separately, and you have them already if you have X.
What should exist, though, is a modern "cursor theme" just recreating these cursors in modern format. Maybe it is not aviable as a package, but as a tar.gz file on some desktop theme collection website.
Oh, realizing you did not explicitly ask to use the original/old cursors - so a theme "looking like them" (in a package) would fully solve your question.
/usr/share/fonts/X11/misc/cursor.pcf.gz. It is a bitmap font - not scalable, and in an old format. But that is all not surprising as these cursors were part of the very first versions of X pretty sure... I manage to get it working on my Linux. Basically, I have downloaded the cursor files from http://blackevilweredragon.deviantart.com/art/X11-Cursors-25788898
Then used convert to make ... well convert them to .png
convert icon:no.cur normal.png The next step is to make the .png a valid X cursor format, so I used xcursorgen
xcursorgen conf.in normal conf.in looks like this:
34 10 4 normal.png 1000 I did this for all the cursors I was interested in, then overwrite the files in the current cursor theme:
root@alexi-XPS13-9333 15:59:40-[x11_cursors]# cp normal /usr/share/icons/DMZ-Black/cursors/left_ptr NOTE: it worth mentioning that some programs will not follow the theme rules (mostly Skype) :)