If you look at
winapp2.ini making those entries is actually rather easy. All it takes is to look at other entries in it to figure out how to make your own.
Below is an
example I've made from the information you've posted. Do note I don't use FlashGet whatsoever therefore I won't be testing this cleaning routine out.
You'll have to verify that:
* The line after RegKey1 is correct, otherwise it won't clean that Recent File List.
* It removes those Default.bk* in FileKey1.
CODE
[*FlashGet 1.73]
LangSecRef=3022
Detect=HKCU\Software\JetCar
Default=True
RegKey1=HKCU\Software\JetCar\JetCar|Recent File List,all
FileKey1=%programfiles%\FlashGet|Default.bk*
FileKey2=%programfiles%\FlashGet|Default.jcd
Other than that I've thrown you a bone, and it's easy to modify it if it doesn't suit your needs.