Ability to plug-in/override Decimal Handler ?

Hey Everyone,
    I haven't ever had much recourse to email the mailing list, as I am 
mostly one of those ORM folks that uses the upper layer. Apologies in 
advance for that ;) However, I have noticed that during bulk operations 
(mostly instantiations) using the ORM that the decimal.Decimal is slow. 
I mean 400seconds slow, when compared to using gmpy.mpq which ends up 
running in 50seconds.

    So, is it possible to overload the pscyopg2 adapter to use gmpy ? 
Currently, I have changed the psycopgmodule to
   
    decimal = PyImport_ImportModule("gmpy");
   
    and

    decimalType = PyObject_GetAttrString(decimal, "mpq");
   
    Which works great, however, I really don't want to fork an entire 
library over a two line change. So. Any ideas/thoughts on how I would 
inform psycopg2 to use gmpy.mpq instead for Decimals in a 'nicer' fashion ?

   
    I am sure there is probably something obvious I am missing :D
    Regards  
    Stef Telford