This makes it too easy:
http://www.easyconnect.linuxuser.hu/

It has saved settings for types of phones, and over 100 GPRS networks worldwide, including digicel-Ja

It requires perl-tk and libwww-perl, which aren't always installed, but easily apt-get installable ;D

Then, it's point and click.

The only hard part (for novices) is determining which /dev it got assigned to...