Using another wxinstall
First, create the target directory (in this article, as an example, ~/aMule/ will be used), where wxWidgets and aMule will reside (they don't need to be in the same dir, but it makes life easier). Then configure wxWidgets and aMule accordingly.
It is recommended that you read the article about how to compile wxGTK
In aMule source dir:
./configure --prefix=/home/user/aMule/ --enable-debug --disable-optimize --with-wx-config=/home/user/aMule/bin/wx-config
make && make install
NOTE 2: Sometimes wxBase will overwrite wx-config. You can know if it has done so by running wx-config --basename. It should show wx_gtk. If it doesn't, please reinstall wxGTK so it will overwritte wx-config to link it to the wxGTK file.
On the above example, aMule binary will be installed in ~/aMule/bin/ directory.
To start aMule, you need to explicitely specifiy the LD path each time you run it: