Unless you have a PSP2000 on 5.00 M33, I don't think there are any in-game text readers. On 5.00 M33 on the 2000, iR Shell had a feature called "advanced multitasking" which allowed you to run a second game or app in the background and switch between them with a key combo, so you could have Bookr running in the background and switch between it and the game.
I don't know of any other way of achieving what you're asking. Although I don't see any reason there couldn't be some plugin to do that. So maybe there is and I just haven't heard of it.
EDIT: A quick google search reveals that there actually are some plugins for doing do; CWCheat is capable of doing it (and I would suggest that other cheat plugins, e.g. TempAR, may well have the same feature), and there is also a plugin called PSPEText.
There may be other options also, I didn't look for too long.