It's not required but seems to be the easiest way. Simply install the Toolkit and VisualAge C++ (without toolkit parts) + fixes.
Here: WPS backup, VAC++ 3 CD excluding the toolkit, edit LIBPATH before the reboot (IIRC x:\OS2\DLL before x:\IBMCPP\DLL), reboot and WPS backup, install the first 3.08.x updates with documented reboot, an extra reboot before installing the IIRC 5th package, reboot, install the toolkit v4.52 by using eCS CD #2. And install optional packages like the lvm_toolkit_15.zip, drgdrp.zip and nb-fix.zip.
I do tend to install *.*, including the IDE. If it's buggy, then just don't use it. Probably easier than having to install VAC++ if some project or programming book requires it. Typically you won't use it, for one because of the famous steep learning curve.
Last known location of the english-us FixPaks:
ftp://service.software.ibm.com/ps/products/visualagecpp/fixes/v30os2/english-us/fixpak8, IIRC you'll need 8 (6, and 3081, and 3082).