Cadillac Powertrain Control Module (PCM) Tuning Discussion, What can be done with an L05? in Cadillac Engine Discussion; What can you do with TBI engines as far as PCM upgrades? I know you can't do anything with the ...
You have to pull it out of the PCM, drop it on a programmer. Once there, maybe 10-30 seconds. You only have 64k max of data, possibly less being a TBI engine. I wouldn't be surprised at all if it was a 32k PROM.
Then you need to get a handful of blank ones, or some EEPROMS (Electronic Erasable PROM's) so you can use one, and erase it when you want to reprogram it. If you do a lot of flashes, get a couple EEPROM's, if you only do a couple, get plain PROMS, they are cheaper.
I am not sure what the L05 uses, probably a 27C256 would be my guess. (EDIT: It uses a 2732.) But check first. Being the parts likely aren't made anymore, you won't see fresh production, but due to the popularity of them, places like DigiKey and Arrow probably have lots still.