wpkg --cmake-generator ...
The --cmake-generator option is the same as the -G option of the cmake command line tool. It spells out the generator to use to generate the necessary makefiles to build a project under your current development environement.
By default, the cmake command line is run without specifying the generator. This may automatically select a default or it may generate an error requesting you to enter a specific generator.
Under Unices, it is expected that you do not specify the generator. By default you get Unix Makefiles which works perfectly.
Under MS-Windows, you may use the default in a cygwin environment or equivalent. However, to make use of the Microsoft Visual Studio environment, in most cases you want to use the NMake Makefiles.
wpkg --cmake-generator "NMake Makefiles" ... --build package-src_1.2.3.deb
Note that if you change the generator, it is likely that you will have to change the name of the make tool as well.