Ah, unfortunately it'll be probably a fair bit more difficult than that to find vertex arrays in memory. The models will only be stored as a .TMD (provided that is indeed the format square used) on the disc, once loaded they will exist in memory as linear arrays of values (16 bit values if memory serves me correctly). I really have to get some time together to have a look with you.
Also, it is a bit unlikely that the geometry will exist in vram, generally it's used to store texture data. The vertex data is more likely to exist in the main memory of the psx. This just brought an interesting thought into my head, i'll start a new paragraph i think

Save states - a save state is actually a complete dump of the state of the emulated system. The state of the system would have to include the exact state of any memory that the system uses, with a discbased system like the sony all the data being used at a given time is loaded off of the disc and into memory. Basically this means that model data exists in save states taken when models are on screen, in one way or another. It would be in the section of the save state that stores the current state of the system's main memory.
If you can find any information about the epsxe save states post it, I had a quick look and found that ram starts at offset 1BA in an uncompressed epsxe save state. Now would be the difficult part, how do we know what data in ram is representing what?
I guess you could get a hex editor and have a look for a series of 16 bit numbers with very few zeros and little repetition. This 'could' be a sign of meaningful vertex data. Then you would either have to copy the sequence and feed it to through a script in blender or write a simple program to load a series of arrays from a simple file and attempt to draw them as a vertex array.
The trouble is I have no idea how the psx gu takes it's texture co-ordinates, normal, spacial co-ordinates ect. I'll make some time on the weekend and have a look. This could make figuring out the order of the vertex array very hard (provided we can identify one).
Also one good thing about this is, we would be likely to find the model's key-frames, meaning we could re-create the animation.
Maybe someone knows a bit more about the way the psx works and can give a hand with this idea. Still unsure if it would be correct though. I'm just hoping that the psx has very little ram otherwise this would be the worst job ever.
Wow, ended up being alot of writing.