Hi man, i have the same Latitude e5420 , after 3 weeks i got a fully working install Lion 10.7.2 
Disable 1394 port in bios and ExpressCard set boot for minimal  
just use iboot (chameleon, stolen and rebranded) from tonycrapx86 blog with last chimera (chameleon, stolen and rebranded) edition don't use Graphics Enabler 
after install boot from iboot (chameleon, stolen and rebranded) again and add some kexts to /S/L/E/ and use MultBeast for Lion and make smbios,plist Boot.plist files 
  
the kexts used was: 
to boot 
FakeSMC 
IOAHCIBlock 
AppleCPUPowerManagement patched With speed_stepper_lion_1072(google it) if cannot found use the NullCPUPowerManagement instead (but no Sleep) 
  
Mouse and Keyboard Both works but mouse don't recognized as a touch (no gesture working ) Google for Synaptics Keyboard Gesture 32 64 
AppleACPIPS2Nub  
ApplePS2Controller 
  
Audio (Semi Work, Master Volume doesn't  work and some glitches at playback music, i can't get intel HDEF working need DSDT hacks and i didn't try ) 
VoodooHDA 0,2.72 from multifail (delete AppleHDA.Kext to avoid Kernel Panic) 
try AppleHDA Patched For Lion  
Use BCM5722D Kext 
  
For Battery  
Voodoobattery kext 
  
Onboard  Bluetooth No kext needed 
Onboard  Webcam No kext needed  
Onboard  wi-fi Not work use a USB or change onboard card 
  
Get Almost Info and next at this sites: 
http://www.kexts.com/downloads.php?do=file&id=1578OnBoard Ethernet 
InsanelyMac or OSX86PC 
tonycrapX86 
http://www.osx86.es