Set up a "Role" named "Always use!", by entering S R R A
(Setup, Rules, Role, Add) from the Main menu,
and enter "Always use!" as the nickname and your identity as:
(Substitute "Full Name" as you prefer, and "usename"
with your own username).
Full Name <username@blackhole.nyx.net>
This will add a line to your .pinerc, like:
patterns-roles=LIT:pattern="/NICK=Always use!/FLDTYPE=ANY" action="/ROLE=1/FROM=Full Name <username@blackhole.nyx.net>/RTYPE=YES/FTYPE=YES/CTYPE=NO"
References: