Not Sure about STICK Drives but you can try Windows In-built Partitioning tool.
Goto Control Panel->Administrative Tool->Computer Management->Disc Management
Here Select your Pen Drive or External Hard Disk or whatever, then Right Click that partition and select Delete partition, after that create the two new ones. If you are using Vista, then you can also split the Drive into two easily.
My pen drive has partitioning software bundled with it so never tried, guess you might look for Partitioning Magic also