copied from the Internet:
Newsgroups: rec.radio.amateur.misc
Subject: FT-470 Expanded Freq Recieve
Sender: daemon@ucsd.Edu

This modification for the Yaesu FT-470 was worked up by Darrel Sego, KM9S,
and was given to me by a Yaesu representative at the Jacksonville HamFest.

This simple keyboard modification allows the FT-470 to recieve frequencies
between 450 MHz and 500MHz.  It does not require opening of the case.

(1)  On the main band, program the frequency 450.00 MHz simplex.

(2)  Press the [F/M] and then the [RPT] button for offset.

(3)  Enter code 0000 into the keypad.

(4)  Turn the radio off.  Then turn the radio back on.

(5)  Press the [RPT] key twice for a "+" offset.

(6)  Press the [REV] button one time.

(7)  The radio will display 1450.00 MHz.  (It does not work at these
     frequencies.  It will recieve up to about 500 MHz.)

(8)  Now, store the frequency of 500.00 MHz into the "U" memory.  Press the
     [F/M] key followed by the "down" arrow key to drop the freq 1 MHz at
     a time.

(9)  Store this into "U" memory.  Press the [F/M] key for about 1 sec, or
     until you hear two beeps.  Rotate the channel selector until "U" is
     displayed, then press the [F/M] key again.  If "beep" is enabled, one
     beep will confirm the storage.

(10) Now store 450.00 MHz into memory "L" for the lower of these expanded
     limits; use the procedure of step (9).

(11) To use the higher frequencies, go to the "U" memory and press the [MR]
     button to place the radio in memory tune mode.  From there, you can
     scan down or use the channel selector knob to select a lower frequency.

(12) Any selected frequency can be placed into a memory channel.

Note:
     Most radios will not let you go up in frequency, only down.  Be sure to
     start at the higher end of the desired range and tune down from there.
     If you try to go up, the rig will default back to the original ham band.

     To rid the radio of this modification, simply reset the CPU.  All
     memory channels and offsets will be lost.

Enjoy and good luck.

73, Mark Eversoll KD4BNF

Note: I haven't tried or verified this, proceed at your own risk.  WA2ISE 
/EX