Hi,
I know exactly what you are talking about! Well,....In the last 6 months or so at least 3 indivduals (from HongKong, Denmark, USA) chose to contact me who initially told me they were planning to study Farsi at Dekhhoda Inst. I helped them as much as I could and, in fact, two of them are still here. Anyway, as for your questions I must tell you that Enghelab Square is quite far from (6miles, 10km) the D.I. and getting the in the morning and getting back home at night would be be quite a nightmarish challenge for you considering Tehran's absolutely horrible and never-ceasing traffic jam specially during rush hours!
So, the easiest way for you to get to D.I. is to look for the so-called 'shuttle cabs' (taxihaye khatti) right near Enghaleb Ave that would take you non-stop to Vanak, from where you MUST and can tranfer to another 'shuttle cab' to Tajrish! Once you are on the second cab ask the driver to get you off near Dehkhoda. Both cabs together would cost you just about 1000 tomans. But be warned it may take you over an hour to get there in the morning...and back home in the evening! No kidding!
having said that, the only 2 other viable alternatives that come to my mind are:
a) call a cab company from your home ( not a shared/shuttle cab!) and get a ride to Dekhoda, which will cost you, i would say, about 3500 tomans. keep in mind you would of course have to pay the same amount coming back home in the evening! so it is a much more expensive transporation system. Let's put it that way.
b) find out if there is a 'direct' bus route from the Enghleb Square to Tajrish and back! If there is, you are in luck and all set! I do not know there is any however. I would have to find out.
