Hi all I have a 98 Buick regal I believe has a faulty BCM. Security light comes on car will not start or will start and die, so my question is I seen a regal with a key in the local junk yard. Can I pull the BCM and pcm off that find the resistance of that key and wire in a resistor of same value and make that work withu car? Any info or advice would be great kinda at a loss with this and am getting tired of just throwing money at her but it is a great car and don't want to part/scrap it..

The resistor trick is only going to work if the ignition cylinder contacts are what is at fault.
If you get a junkyard BCM, and it is the ignition cylinder, which in a lot of cases it is, then you'd have to have the new BCM programmed.
You have a pellet in the key correct?
If so, and you have a multimeter then you can measure the resistance of the pellet, then put the key in, and remove the hush panel above the gas/brake pedals, then at the big wiring block you need to locate the two little white wires that are coming out of the orange sheathing, remove the screw holding the wiring block down, then back-probe them to see if the resistance is close to what the pellet reads as.
If it the reading is off by a lot of ohms, then you could do the resistor trick, or just get a bypass and bypass VATS altogether.
The other option is to have somebody that can tune the PCM tune VATS out of it, I'd rather go with the bypass option personally.
Here is the bypass I am referring to.
Baker Electronix - GM VATS Bypass


Read this thread though first, as you need to determine which type of VATS system you have.
How to bypass the VATS system in a late model GM vehicle

Okay. I guess what I'm wondering is if I pulled the pcm and BCM out of the same car and used a resistor that'* same values as them (junk yard car) then my original key would work because the pellet is bypassed right? And would it still need programmed means I'd use matching pcm and bcm from same car? I've tried a bypass from NEWROCKIES and it was a joke and send back

If you pull a PCM from a donor car then that PCM would still have to be flashed to your cars VIN, and the donor BCM would have to be reprogrammed, as most likely it is not programmed to the same resistance value as the ignition, since there are 12 different ohm values, even if you got lucky and found one programmed to the same resistance, I am pretty sure the BCM would still have to be reprogrammed.
I am sure somebody that knows VATS better than me will chime in and help you a bit.

Have you had the car scanned to see if there are any codes, if the security light comes on, and stays on, never turning off, then it should be setting some sort of trouble code.
You may have to have somebody scan it with a Tech II scanner, then you could be sure it is a faulty BCM before trying to replace it.

As for the new rockies bypass, it works the same way any of the other bypasses work, to my knowledge anyway, they just have to be wired in correctly to the TDM..

Have you went over the thread I linked you to, and read up on testing the ohms at the wiring block I mentioned?
Before thinking it is the BCM, I'd verify the ignition switch is not at fault, it is usually the ignition cylinder contacts that wear out.
If that is the case then you have a few options, one would be to replace the ignition switch.
Or do what I did, I did not have a VATS issue, but I did not want to pay 27.00 every time I needed a spare key, so I cut the wires coming from my ignition, and got a resistor that matched my pellets resistance, then I spliced it into the wiring block directly.
If I ever get the money I plan to put it back the way it was though, as I found I can get keys fairly cheap from E-Bay.
At the time I was not too worried about security, as I live in a pretty crime free area.