Can I customize ANSI colors in Terminal without extra tools like SIMBL? I noticed that colors in the Snow Leopard Terminal.app aren't that great (using the Pro theme, but the other themes are worse).

There seems to be no easy way to customize the colors, and googling only showed weird workarounds involving SIMBL and forcing the terminal to 32-Bit.

Is that still the case, or is there a way to change the colors in Snow Leopard's Terminal.app? My shell is zsh, not bash if that makes a difference.

Clarification: I'm referring to the ANSI Colors like Green, Red, Blue etc. By default, the Terminal looks like this:



These colors aren't that great, I want them look like this:



I have found a 64-Bit compatible SIMBL/TerminalColours plugin, but if I can avoid having to use SIMBL, that would be my goal. I know that there are alternative terminals like iTerm, but I want Terminal.app.
Terminal.app has these colors hard-coded into it. Internal methods like +[NSColor(Terminal) vtRedColor] use hard-coded floating-point constants to set the colors.

As you noted, there are SIMBL plugins that can patch this but you've already noted their current limitations. SIMBL has been updated to support 64-bit applications, so you should contact the authors of the plugins to request that they rebuild them to support 64-bit. There's also another SIMBL plugin to consider.

The only other option for Terminal.app is to write a feature request at http://bugreport.apple.com and hope that somebody at Apple is enticed to add color customization to Terminal.app for Lion.