Recently, I came across a blog post about installing Nano on the Cr-48. The basic idea is the stock Cr-48 setup can use binary packages from Arch Linux. That completely eliminates the need to set up a Chrome OS development system and build the software yourself. I figured if he can do that with Nano, then I can install Vim the same way and after that, running TwitVim would be a snap.
Here are the steps I used:
First, of course, you have to switch the Cr-48 to developer mode.
Next, make the root filesystem writeable.
Download XZ Utils and install it on your Windows, Mac, or Linux machine. You'll need it because some Arch Linux packages are compressed with XZ and the Cr-48 doesn't come with an unpacker for that.
Download Perl from Arch Linux (i686 architecture) to your PC. (not the Cr-48 yet) I got version 5.12 but presumably, newer versions would work too. Decompress the perl package with XZ and optionally recompress it with gzip.
Use a filesharing service like Let's Crate to transfer the file to the Downloads folder of your Cr-48. Alternatively, you can scp the file from your PC to the Cr-48 if you have sshd on your PC.
Open a shell on the Cr-48 and unpack the perl package in the root directory. The files should go into all the correct places in the directory structure.
Repeat the same steps as above to download and install gpm.
The Vim installation is a bit more tricky because the Cr-48 comes with glibc 2.10 but the latest Vim binaries in Arch Linux require glibc 2.11. Of course, you can upgrade glibc if you're really careful but there is potential for messing up the system. Instead, you could use an older Vim binary package that was compiled with glibc 2.10.
I used Vim 7.2.266 from the archive of old Arch Linux packages. It's already gzip-packed so you can download it directly to the Cr-48 and install it.
And that's it! The Arch Linux Vim comes pre-built with the Perl interface so it is ready for TwitVim installation. So download a copy of the latest TwitVim vimball archive to the Cr-48. Then run Vim and install the vimball archive. Note that I haven't found a way to set up a browser command in TwitVim on the Cr-48 yet, so when you run :SetLoginTwitter to authenticate with OAuth, TwitVim will present you with an is.gd shortened URL. Write that down and switch over to Chrome to enter the URL, which will take you to the Twitter OAuth login.