I'm afraid you can't use VB6.

The closest match is eVB (a free download from MS, as part of an old version of "Embedded Visual Tools"), which uses VBScript. There are a few differences in coding, and eVB is not supported on PocketPC 2003 or later.

VB.Net has the Compact Framework which allows you to write for Pocket PC devices, and I would recommend using this if you can.