The SDK is what you want, specifically SpeechSDK51.exe. That's a self-extracting archive. You can run it using CrossOver's Run Command feature to extract the files.
The problem, though, is if the SAPI 5.1 installer thinks it's running on Windows XP, then it figures that several of its components are already installed as part of the OS, so it doesn't bother installing them. Since you were installing into a winxp bottle, the SAPI installer was leaving a bunch of stuff out.
If Streets and Trips should work under Windows 2000, you might try creating a win2000 bottle. It may be that Streets and Trips will then install what it needs. (It should ship with the necessary text-to-speech engine, but not all programs ship with everything they depend on.) If Streets and Trips doesn't install the engine it needs, you can install the SDK as unsupported software into the bottle. Select the SETUP.EXE that was part of the SpeechSDK51.exe archive.
If Streets and Trips requires Windows XP, then you have to do a little dance with the bottle's Windows version setting to get the SAPI installer to install everything:
- In the Manage Bottles window, select the bottle
- From the Control Panels tab, launch winecfg
- At the bottom of the winecfg window, select Windows 2000 as the Windows version
- Click Apply, leaving winecfg running
- Install SAPI 5.1 into the bottle as unsupported software; when CrossOver asks for the installer location, select the setup.exe from among the files obtained by unzipping SpeechSDK51.exe
- After that completes, set the Windows version back to Windows XP in winecfg
- Click OK to close winecfg