If you use the MLD dev environment, and take the MLD kernel package, the resulting kernel is exactly the same as the MLD images include.
In the kernel folder you can call "make menuconfig" to change the kernel configuration. After that a simple "make" will build the changed kernel package. This will not rebuild the whole kernel, but only the necessary part of it. This needs mostly only a view minutes. To rebuild the whole kernel you must do a "make clean" first.
To also build all depended packages, you can do a "make all_depends" in the kernel folder.