might be interesting to you too...
are you aware of diald? if not then that's definitely what you want to be looking at. It uses the ppp scripts as well tho. scripts like that aren't really that standard. my old ppp script was:
/usr/sbin/pppd /dev/modem 57600 debug user qp.fsnet.co.uk \
connect "/usr/sbin/chat -v '' AT OK ATD08089933006 CONNECT '\d\c'"
all just one line that i sussed out over about 30 mins of trial and reading the pppd man page.