From OSSEC Wiki

How to perform a binary install on systems without a compiler?

1-First of all, download the OSSEC package corresponding to the version you want to install and unpack it (IN the system with a compiler).

 # wget http://www.ossec.net/files/ossec-hids-1.5.tar.gz
 # tar -zxvf ossec-hids-1.5.tar.gz

2- Enter in the source directory of the downloaded package and compile OSSEC:

 # cd ossec-hids-1.5/src
 # make setagent                (run this if you want the binaries to install as an agent)
 # make all
 # make build
 # cd ../..

3- Change ossec-hids-1.5/etc/preloaded-vars.conf to set BINARY_INSTALL to yes.

echo "USER_BINARYINSTALL=\"y\"" >> ossec-hids-1.5/etc/preloaded-vars.conf

4- Create a new ossec package:

# tar -cvzf ossec-hids-binary-v1.5.tar.gz ossec-hids-1.5

Now you just need to use this new package on all the agents (when running the ./install.sh it will use the pre-compiled binaries).