Different proxy for lan and dial-up in IE

Hi,

I have the following problem. I made a small program in VB for changing values of proxy address and port in IE. It uses functions with direct access to registry. It changes values under HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ProxyServer. The problem is that it affects only lan proxy settings, but not dial-up proxy settings.
How do I change values for both proxy ?

Thank you

David