To use a crossover program in linux as a helper app in a program that will not accept command arguments like Thunderbird you can make a symlink.
For example, you have MS Office installed and need to use word to open an .doc file from a Thunderbird e-mail.
You need to go to your .cxoffice dir in your home dir.
cd ~/.cxoffice
Then find the link to the application. You might just want to look in the "Scripts" dir.
find . -name "*application_msword*"
This will find a unique pointer to the word app under crossover.
./win2000/desktopdata/cxassoc/Scripts/cxoffice-880c9208-c4ee-4e75-be5c-1c1d06d8762f:application_msword::open
Now, symlink the binary for easy use:
ln -s ./win2000/desktopdata/cxassoc/Scripts/cxoffice-880c9208-c4ee-4e75-be5c-1c1d06d8762f:application_msword::open openword
Then point thunderbird over to the symlink.
