I must stress though, that our dev team is reluctant to add just about any coin unless that coin is really supported / used by the community.
Surely embracing the open source nature of your product would be another way to handle altcoin implementation? Then Satoshi Labs just need to review the code, which still takes time, but still less time than writing/testing the code too (not that I'm interested in using altcoins with the Trezor myself)