Whilst I'm fresh from getting CAII working on Win 7 64-bit, here's how I did it:
1. Download / locate your CivAssist_II_Setup.msi file. Kinda important that one.
2. Create a folder called C:\DotNet (or whatever) on your PC.
2. Download the .NET 1.1 framework redistributable package, which is called dotnetfx.exe, into this folder. Get it here:
http://www.microsoft.com/en-us/download/details.aspx?id=26
3. Download .NET 1.1 SP1, from here:
http://www.microsoft.com/en-us/download/details.aspx?id=33. Save this in the same folder as the previous download. Rename it something easier to type if you like, e.g. dotnetfxsp1.exe.
4. Make sure you're logged into Windows as an Administrator.
5. Open a command prompt (Windows-R, cmd, OK).
6. cd C:\DotNet
7. Run dotnetfx.exe (there may be a prompt about compatibility issues, ignore it and continue on to install)
8. dotnetfxsp1.exe /Q /L:C:\DotNet\dotnetfxsp1.log
9. The .NET installation is done, now install CivAssist II. If all is well, it'll detect the right version of .NET 1.1 and run.
10. Right-click on the CivAssist II icon, select the Compatibility tab, and select Compatibility with Windows XP SP3.
11. CivAssist II should now run.