I've found another way to install Chrome in that situation. (This is
not recommended for unexperienced users because it may cause problems
on updates and uninstallation. I haven't tested thoughtfully yet.)

The directories listed here are applicable in Windows Vista.

1. Run ChromeSetup.exe
2. Open C:\Users\<USERID>\AppData\Local\Google\Update\Download
\{7FA2199A-FCB7-48AC-B5DA-83B145DE5D00} (The last hex-codes may be
different. It changes on every downloads...)
3. Open chrome_installer.exe with 7-zip client and extract chrome.7z
from it.
4. Extract chrome.7z again. Then you get a folder called chrome-bin.
At this point, chrome.exe won't start even if you launch directly
here.
5. Copy all contents to C:\Users\<USERID>\AppData\Local\Google\Chrome
\Application
If there's no such folders, create it.
6. Move all contents (dlls and others) in C:\Users\<USERID>\AppData
\Local\Google\Chrome\Application\0.2.149.29 to C:\Users\<USERID>
\AppData\Local\Google\Chrome\Application\.
7. Run chrome.exe, then you might see the "first run" process.
Here, I failed to import existing bookmarks and settings because it
just became frozen after I clicked "next". But it created "First Run"
file and I could use Google Chrome finally.

This is kind of a manual installation. I'm not sure what the installer
writes on the registry during the original process.