Postpaid or prepaid?

These are the settings I use for celcom PREpaid/xpax, which is not found in the link JasLyn provided:

In SwirlyMMS > Settings:
MMSC: http://mms.celcom.net.my/
Proxy: 10.128.1.242:8080
APN: celcom
Image size: Medium, but i've not tried the other settings

I left all the other fields blank.

And not sure if this is required, but
In Settings > General > Network > Edge
APN: celcom

To receive mms notifications, you don't need to turn on Edge in BossPrefs. To retrieve them, you need to.

Oh ya I forgot, you need to call celcom to activate gprs for your number as well...