i have the mcx462 as well. my motherboard/case combination precludes using a 120mm fan adapter (collision with the PS), so i got a 80mm-to-92mm fan adapter. the only off-the-shelf one i could find was the Amuzuma Fan Adapter, which actually allows you to mount 60mm/70mm/80mm/92mm fans to 60mm/70mm/80mm/92mm mounting holes. it was also an open-air adapter. depending on the fan and heatsink, open-air adapters can be better than funnel adapters. this is especially true for slow speed axial fans since their P-Q curves derate heavily. (on the opposite note, funnel adapters might work better for high pressure fans in highly turbulent heatsinks, like the cross-vein axial delta fans on a mcx, but since this is a silent crowd, i don't think many of the audience here use this combo!).
here's a link for a picture on a retail site for the adapter:
now the unfortunate news. as far as i know, amuzuma i think is no longer in buisness since their webpage is down. sidewinder computers used to carry them, but they are sold out.
on a related note, i've seen DIY non-backpressure adapters with the same type of geometric template on forums, and they didn't look too complicated to build if you have some spare time.