How to upgrade an HTC Magic (32B DEV) from Android 1.5 to latest Android?

Last year I got a free Android phone at a Google event, and I would like to upgrade it to the latest Android version (probably with Cyanogen).

What is the quickest/safest way to do the upgrade?

It is a developer phone, so:

• The Cyanogen instructions do not mention my phone.
• I have no data plan, but the above instructions say "data plan required" (workaround)

HTC Magic, Model Number GDDJ-09, Build CDB56, Android 1.5, details:

SAPPHIRE EVT1 32B DEV S-ON G
HBOOT-1.33.3005 (SAPP20000)
CPLD-10
RADIO-2.22.19.26I
May 29 2009,14:38:09