Then in ida look for something that says
nvram boot-args="" then insert that so itll look like this
nvram boot-args="-v debug=0x9"
see if thatll work
is not so easy.. you can do what you're saying to the terminal from the Mac and iPhone OS up to version 1.1.4 (if I remember correctly) because Apple has disabled the boot-args.
For iPhone 3GS, iPod touch 3G, and A4'users it can be done because they have the exploit limera1n (tethered) ... are you expert of Ida? if yes, I post an image so you can help me ...