how to set APN for GPS location aiding?

Hi,
I upgraded to version .545 - now my GPS menu changed slightly.
There are only two buttons: 1 to turn on or off GPS and one to enable or disable location aiding - I'm sure there have been 3 before. I was always wondering what the difference between the lower 2 buttons was.

Anyway, I face another problem: Is there any chance to define what APN location aiding uses?
My BlackBerry works on 2 different APN - one for BlackBerry Service and one for Wap/WebBrowsing.
I get charged for the Web browsing; Blackberry is included with my contract. I never use WebBrowsing over that WAP APN (since I can Browse over BES for free) so there is no traffic on that APN. However every time I start GPS my BlackBerry generates some bytes of data traffic. Even tough these are just some bytes I get charged for 100kB each single session - and that sums up.
I already set the APN for TCP/IP to the free APN but that doesn't help.

Turning off location aiding does help - but renders GPS almost useless since it takes minutes to get a GPS fix.

Any ideas?