Need help cracking a wpa2 handshake

I am trying to crack a 8 digit, lower case password, I normally brute force these within 1 day with 5 x 29 290x.

Today I learned that the passwords don't contain the characters I and o, and I could speed up my attack if I could get hashcat to ignore/skip those 2 characters.

Is this possible with the brute force attack or will I have to use a dictionary?
I don't even know what a rule based attack is so I hope this isnt going to be complicated.

thanks