ota update over thunderom

No. It'll break the Rom and might even brick the phone. An update from market for a particular app does no tbreak the Rom.
 
Download the LG mobile update program you can find it in one of the srickies on the main page. Once installed plug in your phone and run the update from there, if there are any problems make sure you make a back up prior to running the update, you may have to reflash your ROM so make sure you have titanium back up as well to restore all apps and data