Doesn't the vacuum modulator simply screw into the side of the transmission ?If so might be worth a shot at putting it on yourself...
but I would keep doing the driveway shifting through the gears with it running a little each day.... if an orifice has some flow through it the varnish can dissolve pretty fast.. but if it was completely clogged then it will take longer..
There is a moderator on this site ... Steve Brotherton... that has a transmission info site that is great.... you will need that info if you put the new modulator on ....