Cannot Upgrade to ICS via OTA or LG Tool

[mel2000]

Recently purchased a refurbished LG Spectrum with Android 2.3.5.
OTA in Settings menu won't update due to network being unavailable (no mobile account and no SIM card yet), although I have WiFi.

LG Mobile Support Tool won't let me update because it wants me to use the the Verizon Update Assistant tool, which I am not prompted for since I don't have a Verizon account. No way to override.

Will I be able to upgrade via OTA once I have an account with a Verizon reseller? Is there another way I can manually upgrade to ICS 4.0.4 without the Verizon or LG upgrade tools?

TBH, I'd prefer to install a recovery (TWRP preferred) and a rooted stock 4.0.4 ROM. Hopefully, everything on the phone will still work. I'm open to suggestions. Thanks.

 

[mel2000]

The Verizon Software Upgrade Assistant (SUA) tool did not previously popup on my PC because I had disabled autoruns. I was able to successfully upgrade to 4.0.4 by setting my USB connectivity to Modem mode. The SUA showed up as a CD icon in Windows Explorer and I was able to launch it by double-clicking the bootstrap.exe file. I'm ready to root ICS now.