Downgrading from vm510pv8 to vm510pv7

[ProPro]

Hi, im new to the forums, but i know my way around technology pretty well. I have a new rumor touch for virgine mobile with the version of firmware that doesnt show the "SD CARD" folder in the "My Stuff" folder so that i can use 3rd party apps. I figure the best way to fix this is to downgrade the firmware to the previous version (which i know works). I already have my spc code and have unlocked the phone into dm mode and have lgdownloader and all that jazz, but im not sure how to the actual downgrade, or even where to get the required files. Can anyone help me with this problem?

[ProPro]

Sorry for double post After snooping around, i found the folder containing my demo to "midnight bowling". I tried deleting the jar and jad for that (21.jar and 21.jad) and replacing them with the app i wanted (named them both "21" before transferring to the folder). When clicking on midnight bowling in the phone, the app starts and it displays the name of the app i wanted (like it is starting up), but then just goes back to the screen that lists the games. THis is about the extent of what i can do unless someone points me in the right direction please.