I have some experience with this issue, since I am currently hosting a small thing over on OpenShift. Not completely sure why, but things don't always get installed in the same place on different hosts. OpenShift beening one of them. In my case, what I did was ssh into your server and run :
find . -name phpize
Write down the path to phpize that is found, then you will have to open the phalcon installer (install, found in cphalcon/build) with vim or nano and edit the paths to phpize to reflect what you found from the query above.
For example, on OpenShift, I had to change my section of the installer, where it calls 'phpize' to look like the following:
#Check processor architecture
if [ -z $1 ]; then
DIR="${OPENSHIFT_REPO_DIR}/cphalcon/build/32bits"
gcc gccarch.c -o gccarch
if [ -f gccarch ]; then
P64BITS=`./gccarch`
if [ "$P64BITS" == "1" ]; then
DIR="${OPENSHIFT_REPO_DIR}/cphalcon/build/64bits"
fi
fi
else
DIR=$1
fi
#Move to specified architecture
cd $DIR
#Clean current compilation
if [ -f Makefile ]; then
make clean
$OPENSHIFT_RUNTIME_DIR/php5/bin/phpize --clean
fi
#Perform the compilation
$OPENSHIFT_RUNTIME_DIR/php5/bin/phpize && ./configure --enable-phalcon --with-php-config=$OPENSHIFT_RUNTIME_DIR/php5/bin/php-config && make && make install && echo -e "\nThanks for compiling Phalcon!\nBuild succeed: Please restart your web server to complete the installation"
Hope this steers you in the write direction. PaaS services are great, but be perparded to get to know your server.