No, you can't pass an Id to the Go to Record [ ] script step.
You could try a Go to Record [ next ] in a Loop with Exit loop If [ Members::KP_MemberID = $MemID ]
( note the single $, you don't need a global variable )
Go to record goes to the record by it's position in the current found set.
Go to record  is the same as go to record [first]
Go To Record [ 35 ]
goes to the 35th record in the current found set--which might have 2345 as it's primary key value.
I can see that your looping idea will work. But, isn't there a better way that will not produce the 'flicker' or CPU cycles that going through the entire found set causes?
I can't think of anything.
Freeze Window to elminate the flicker.
I do not think that you'll see a flicker but, in that case, you coud freeze the window.