Choose from the following working downloads of Watchmaker Suite.
Alan Canon has packaged the tools required for Watchmaker development under Windows, including a bundled copy of a correctly configured version of the SheepShaver emulator.
SheepShaver for Windows, with bundled hard disk image containing a minimal OS 9.0.4 install (includes Carbon 1.6 update, Stuffit Deluxe, and SwitchRez):
http://alancanon.net/mac_resources/SheepShaver/SheepShaver_MacOS904_20150127.zip (122 MB).
(Alternatively, you may use the Watchmaker Suite SheepShaver for Windows edition, which is based on the above disk image, if you've already downloaded it.)
Development tools hard drive image for SheepShaver (use the SheepShaver GUI to add the unzipped disk image to the list of drive images.)
http://alancanon.net/mac_resources/SheepShaver/SheepShaver_CW71Pascal_20150127.zip (205 MB).
You will then need to download and import the latest version of the Watchmaker Sources from the "Files" section of this sourceforge site. Unpack them on the "System" drive of the emulated Macintosh.