Standard MIDP2.1 and CLDC 1.1 doesn't have classes to let you use TTF fonts. The typical way of doing it, is to use a bitmap font. Bitmap fonts are fast to render, and lets you use a lot of colours (if you wish). The downside of bitmap fonts is that, in order to support multiple screen resolutions, you'll have create different sizes of the font.
http://mobilefonts.sourceforge.net/
But like any other platform, someone has of course developed a TTF library for JavaME (called TTME)
I remember checking out TTME some time back, and as expected TTF rendering is slow. (Because most JavaME enabled devices have lower-end CPU's and such).
My advice is to go for bitmap fonts or use individual PNG files for labels.