I struggled for a number of hours to get this working, but, finally found the right combination of files and procedures. The key is using legitimate MFC DLLs from a valid Windows XP install. I haven't tested using other WINE installs (or using win98 or win2000 bottles within CrossOver). They may work. But, what follows I know works.
Requirement: You must be using a Mac with the Intel Duo Core Processor.
1. Download CrossOver
Download a 30-day trial version of CrossOver from CodeWeavers at http://www.codeweavers.com/products/cxmac/download_trial/ (the for-sale version only costs $60).
2. Install CrossOver and quartz-wm
At the end of the installation it will request you insert Disk 1 from your Mac OS X install disks which came with your Intel Mac. This is important as a small file (quartz-wm) needs to be extracted from the X11 package. If for whatever reason you don't see a dialog indicating that this was successfull (happened to me 2x), delete all installed CrossOver files and try again.
3. Create WinXP Bottle in CrossOver
At Configure/Manage Bottles within CrossOver create a new winxp bottle. You can name it anything you want. For here, I'll refer to it as the winxp bottle. This will create a bottle stored within your user folder (see path below).
4. Copy/Paste MFC DLLs
From within your valid, licensed copy of Windows XP, navigate to the system32 folder and locate the following DLLs: mfc40.dll and mfc42.dll. Copy these to your Mac and then move them to the equivalent WinXP "bottle" within your user folder. The path is username/Library/Application Support/CrossOver/Bottles/winxp/drive_c/windows/system32/.
5. Copy/Paste wingding Font
To properly show symbols and arrows, locate the wingding.ttf file in your Windows proper installation and copy it to your CrossOver installation in the /windows/fonts/ directory.
6. Install MT4
Download the MT4 installer (e.g. mt4setup.exe) from your broker. I tested using FXDD's latest MT4 build 205. Double-click on the .exe and it should take you to CrossOver and begin running the MT4 installer the same as you're familiar with when running on Windows. Select all of the default options for where MT4 will be installed. At the end, de-select (this is important) the option to auto-launch MT4 after installation is completed. (This doesn't work.)
7. Launch MT4
From within the CrossOver application, go to the Programs menu and then select the MT4 application (it may be within a sub-menu with a symbolic link to the actual terminal app).
MT4 should launch and look just as good as from within Windows! And, MetaEditor launches as well! (Although I haven't yet tested it much.)
There are some minor quirks I'm noticing. I'll keep a log of them as they are discovered. But, trading works, keyboard shortcuts work (except for where there exist conflicts with other system level keyboard shortcuts such as with F9) and placing objects on charts works.
I'll likely update this post with a pointer to a Web site where I'll keep track of this.