Hi Tokka. Apache is not part of DS-Mod (yet). I guess I will make it available in one of the next updates, at least the build procedure. I am unsure if it would be a good idea to include such a big binary into a firmware image. Well, Apache itself might be okay, but definitely not PHP. On a NAS or USB stick, though, it is an interesting option for some users.
For now, just download the precompiled binaries for your box (kernel 2.4 or 2.6, respectively) and put them on an external storage medium attached to your box. Just start it from there, after the medium has been mounted. I would not wget the binaries into your RAM disk, if you can avoid it. You will need the RAM for having the software run, but not to store it. If running Apache from a USB stick, take care to configure it so that all log and lock files are created in the RAM disk or on another storage medium not based on flash technology. Writing too often onto a flash medium will wear it out quickly, rendering it unusable one day. And things like swap space or log files which are continuously written to are very bad for a flash stick, indeed.