I need to make an encrypted file on a PC that I can burn to CD and give a mac user who wants to decrypt it without having to install a program? is this even possible? thanks
The only way I know of is by putting the file inside a ZIP archive with password.
These can be unpacked with the standard unzip on the Mac.
Anything else requires addon software on the Mac.
Here are the instructions to make Truecrypt portable for the Mac. (by dragging the ".app" to your cd/usb).
Otherwise you'll need to use software which is standard on both computers.
Is "zipping" it with a password not an option?
If you are going to use a zip with password make sure to use the strongest encryption available to both systems. The older encryption methods are relatively weak.