All ASMLib installations require the oracleasmlib and oracleasm-support packages. The oracleasm kernel driver is included in the Oracle UEK kernel. Perhaps you are missing the oracleasmlib package. You can download it from:
Oracleasmlib is not necessary for ASM to work, but it contains software necessary for Linux oracleasm, including the /usr/sbin/oracleasm-discover utility, which the Oracle installer used in the previous 11g version to detect available ASM volumes.
I have both packages installed (oracleasm-support & oracleasmlib) along with kernel 2.6.39-400.109.5.el6uek.x86_64.
Been told this morning that I must install something called "Oracle grid infrastructure" in order to use ASM before installing the database software.
This is crazy to me because I have already used the packages mentioned above to create a ASM drive.