According to the Linux Foundation OpenPrinting Database the Canon Pixma MP450 is only partially supported under Linux, and not yet in the Foomatic packages: http://www.openprinting.org/printer_list.cgi?make=Canon http://www.openprinting.org/show_printe ... IXMA_MP450
However, as you will see on the above-mentioned page, someone has used the MP160 driver with it.
However, you could try using the following procedure: viewtopic.php?f=23&t=13528#p77601
see the table in http://gentoo-wiki.com/Canon_Pixma_Series
, but I don't think the i450 is the same as the MP450, is it?
EDIT: Just seen that the first Web page I referred to above has two entries: "PIXMA MP450" and "PIXMA MP-450". The second of these is: http://www.openprinting.org/show_printe ... xma_MP-450
which states that the MP170 driver (CUPS/Gutenprint) "works well".
You could of course buy the commercial Turboprint driver, which apparently works well. Don't know if it supports the scanner though, so you'd have to contact Turboprint to find out.