PPTP on Wan Interface - Obtain IP via DHCP

[zipeee]

My cable modem / Infrastructure provider requires a PPTP logon to access the Internet over the WAN connection.  I noticed that PPTP configuration option on the Interface requires a manual/static input of the IP address of the Local IP address, but my provider issues this out dynamically via a DHCP server.  (The remote IP address is static though.)  Is there a workaround to get the local PPTP address assigned via my provider's DHCP server?

Cheers and TIA,
Z