[Icom] programming UHF radio help

[Bill NY9H]

i bought a ic f420s...( from one of those auction sites)

it's a cute little 430-470 , which works fine.
I have the programming software  iccf300  for 300 & 400 radios.
I have the little mini to rj45 adapter ( icom brand )..

I am having a problem communicating with the radio.
What , if any , is the command to tell the radio to accept programming???
Is it powering on with one of the other panel buttons pushed ????

I am using the regular icom interface which runs my 756pII and programs my 
F10 handheld.

tnx

bill