Compiling for linux? e.g on Ubuntu 13.04 64bit it should work like this
1. update your apt sources
sudo apt-get update
2. install necessary packages
sudo apt-get install bzip2 git git-core subversion checkinstall build-essential libssl-dev libboost-all-dev libdb5.1-dev libdb5.1++-dev libgtk2.0-dev
3. get source files from sourceforge
wget http://downloads.sourceforge.net/project/primecoin-hp/0.1.1-hp4/primecoin-0.1.1-hp4.tar.bz2
4. check downloades files for sha1sum: deb2673c5c8036ede4a2d1e944ce8b0e59e26c56
sha1sum 0.1.1-hp4/primecoin-0.1.1-hp4.tar.bz2
5. unzip
tar jxvf 0.1.1-hp4/primecoin-0.1.1-hp4.tar.bz2
6. enter source directory
cd primecoin-0.1.1-hp4/src
7. make
make -f makefile.unix USE_UPNP=-
8. after the make process you'll find the binary primecoind within the src folder. just start it with:
./primecoind --daemon
9. if you want the qt client change directory
cd ..
10. qmake
qmake bitcoin-qt.pro
11. make
make
after the make process you'll find primecoin-qt in the directory, launch with
./primecoin-qt
12. start mining with the command line client:
./primecoind setgenerate true
13. watch what primecoind is doing
watch -d -n 5 './primecoind getmininginfo && ./primecoind getdifficulty && ./primecoind listtransactions "*" 1 0'
Ah, somewhere in between you have to make a primecoin.conf file in ./primecoin. Do so...