There is a setting on the System Preferences.app Defaults. but it seems to be broken since it seems to do nothing.
I looked into the Terminal.app code myself since I also use it and hate how it looks (the fonts).
The API needed to disable anti alias seems to be missing for some reason.
if you are building gnustep yourself, there is a temporary hack you can do if you are using the cairo backend.
go into core/back/Source/cairo/CairoGState.m
Look for the method named - (void) DPSshow: (const char *)s
you need to add the following lines:
cairo_font_options_t *options = cairo_font_options_create();
cairo_get_font_options(_ct, options);
cairo_font_options_set_antialias (options, CAIRO_ANTIALIAS_NONE);
cairo_set_font_options (_ct, options);
Do so right after
cairo_set_source_rgba(_ct, c.field[0], c.field[1], c.field[2], c.field[AINDEX]);
This is a HACK that makes that API always draw without antialias.
then build the back folder and install it.
I will start another thread on the missing API issue.
Thanks
Luis