After market amp and sub into a W140

[meri_gadi]

hi there everyone. im wanting to install an amp n sub in a W140. but i can seem to take the RCA leads in the back. getting stuck at the rear seats.
has anyone dun this before? any ideas or any write ups. i cant seem to find any.
please help...anyone?

 

[Sp!ke]

u cratin yr pst on yr fn?

 

[meri_gadi]

better???