Yes, it is permissible to follow other than your main madhhab on one or more specific points. But it is highly recommended to acquaint yourself in depth with the fiqh of one madhhab and with its methodology, so that you can better understand the intelligence of its method and that of other madhahibs.
For example, my Grandshaykh, Shaykh Nazim, follows the Hanafi madhhab in fiqh. However, I never prayed fajr behind him except I saw him make qunut al-fajr in the second rak`a every time, and this is required only by the Shafi`i school.
What is not permissible is jumping from madhhab to madhhab to take the dispensation (rukhsa) each affords. Allah knows best.