Im on my phone right now but its simple.
Get a car or a bike
go to any lsc
upgrade it so it cost more
set your respawn at last location
sell it
press start go to online/swap characters
press x if you're on ps3
select your current character
you should respawn near lsc or inside it(doesnt really matter) in the vehicule you just sold
Go back inside lsc
sell it again
repeat
edit
I thought they patched that glitch breh?