The /usr/lib/linuxconf/lib/ppplogin has been debugged and can support both pppd 2.2 and 2.3 option set. This ppp login script is probably the only one you ever need! No more "per customer" login script. Well... that's the goal anyway :-)
The generalized ip-up/ip-down are missing though. Those script simply use /usr/lib/linuxconf/lib/pppparms to learn what has to be done for a given account.
One check box in the pppdialin defaults lets you switch between pppd 2.3 or 2.2.