I don't know about WAP, but these GPRS settings work for me:
Modem > Cellular line (GPRS)
Access point name > internet.be
User name > mobistar
Password > mobistar
Under Advanced... > Servers: "Use specific server adress"
DNS > 220.127.116.11
Alt DNS > 18.104.22.168
Mobistar has two programs, one where you pay 6€ a month for 2Mb and one where you pay 15€ for 10Mb. As far as I know, only the second one works for pocket pc phones (as I discovered after months of frustration and talking to about 10 Mobistar helpdesk-guys).