It's not built to work like that. What you can do is use dmenu. The default is mod1+p. In dmenu, you can type the first few letters of any program and it will usually complete the program and launch it.
You could also use something like xbindkeys. https://wiki.archlinux.org/index.php/Xbindkeys
There's the spectrwm window manager as well. That has a text configuration file and you can have the window manager reread it. I have a page on it at http://srobb.net/spectrwm.html.
However, even on a really slow machine, making the changes to dwm and recompiling only takes a few seconds. I have a page on dwm with a link to good article on the Debian wiki about it. http://srobb.net/dwm.html