You don't need the wireless.sce premade extension if you want small size, wireless.sce is made for beginners to get up and going easily. And has all available firmware, that is the reason for it's size.
The two minimal packages you need are wireless-tools from ubuntu, the package itself is 299.0 Kb. Also the wireless-5.4.3-tinycore64 package.
The wireless-5.4.3-tinycore64.tcz package in Core is 3.6 MB, the wireless-5.4.3-tinycore64.tar.gz package in dCore is 3.8 MB, not a whole lot of difference in the size of the modules package. There will be some size addition to wireless-tools.sce when imported, it depends on libiw30.
You can make a kernel modules sce out of the files you want from wireless-5.4.3-tinycore64.tar.gz for smaller size, just make sure you include any needed module dependencies.
EDIT: At home on dCore now, it appears the iwlwifi.ko module depends on the cfg80211.ko module, from looking at /lib/modules/5.4.3-tinycore64/modules.dep file.