changing a process priority from another application

[mt_samiei]

Dear all we have a program(binary code) . We want to make it to have high process and thread priority. is there any function or way that we can do this from an application which we write to make that program have high priority? Also we have one Device driver which has one kernel mode thread in it. Is there any way to change the priority of system thread of that driver? we have only .sys version of that driver. Regards Monhi