Hiya Wart,
There are two options...
First, As WP34 mentioned you would have to take the rod to a rod builder and have the winch changed. This option can cost a couple of hundred bucks depending on the make and size of the winch you choose.
Second, the POMMIES have a number of triggers which 'zip strap' onto STD winches. This option is adjustable and removable and comes at a fraction of the cost of a perm trigger.
I saw these on many guys rods when I lived in the UK, but I recently saw Hooked fishing with one on one of his AFAW rods. Try sending him a PM, maybe he can source them for us local guys?