The proper way to put the t-case into 4wd is with the clutch in or transmission in neutral. While rolling forward (5mph or less), pull the transfer case lever back into 4wd. You can put it right into 4 low if you want to, from 2wd.
I roll forward in 1st gear at idle, slip it into neutral then move the 4wd lever into 4 low and push my shifter to first. By the time I have done all of this it normally slips right into 1st gear without using the clutch