Did you compile apache yourself or get it from somewhere else?
As far as I know you specifically need to enable APXS support when compiling apache - if you got a binary distribution of apache, it might be that whoever you sourced it from did not include APXS support when configuring and compiling apache...
You best approach (if this isn't what you've done already) might be to download a source archive of the latest apache version (I think it is 2.0.54 which you already have) and compile it yourself.
It's not that hard, try the following steps:
1. Get the source archive.
2. Unbzip / ungzip it with either
tar zxvf archive.tar.gz
if you got a .gz archive, or
tar xvf archive.tar
if you got a .bz2 archive.
3. Change into the resulting directory.
4. In the apache source directory, type
./configure --help | grep apxs
5. If you just get your terminal prompt again, with no info about an apxs entry also try
./configure --help | grep APXS
6. This will show you what configuration option to set to specifically enable APXS, if any.
7. Now, once you have the needed parameter do
8. Wait untilt he configure completes, then do
9. Wait again. When done, and you have your terminal prompt back, become superuser by typing
end entering your password.
11. This will then install apache.
Try and install a module again, most likely you will now have APXS support for the modules you need to install...