I did use it to drive the eyes, and for the drive wheels. I checked my code and for the eyes I guess I am using pulsout pin,49,b1. The diference between th 63 I stated above and the 49 now is probably the difference between an x1 and x2 (4mhz and 8mhz). In ether case, use the wizard to find out what # gives you a range between 0 and 255 --it will make everything else easier...
pwmout 1,49,0pwmout 2,49,0
The frequency should not be a big issue for the LEDs but remember that your picaxe cannot drive the PWM outputs and servos at the same time as both commands use the same internal timers.
Since the frequency isn't too important you can write your own code to PWM the LEDs. I just use a counter to count the program loops. Every 100 loops it resets to 0. Then compare the duty cycle you want (eg. 67%) with the counter. If the counter is less than the duty cycle then the LED is on.
Usually for LEDs 5% resolution is enough. In that case have your loop counter reset every 20 loops. The 67% example I used before would become 65% so your LED would be on for 13 loops and off for 7. This low resolution approach will help eliminate any noticeable flicker that might occur if you program is slow or complex as it will increase the frequency x5.
Tri-colour LEDs are normally just 3 LED dies in a single package, so they behave the same as 3 seperate LEDs. Changing the PWM frequency won't have a significant effect unless you're below ~60Hz.
I have had better luck using the pwmout as an init. and from there using the pwmduty command. You don't need to tell the picaxe to change the pin it goes to PWM as soon as you use the command. Oh, and the variable should be at the end. Use the pwm wizard, it will help a lot.
Also, I use this: pwmout pin,63,b1 --the "63" puts the variable in a range of 0 to 255. 0 is off and 255 is full speed. Obviously, 0 to 255 is a little easier to work with when writing code.