How do you change all the front oil seals on the 1994 GS 300 Lexus

1994 Lexus GS300 4 dr 3.0L engine has bad oil leaks in the front of the engine both sides of the #1 and number 2 timing chain covers where they join. Everything I have read says it is the tension pulley gasket which is leaking. Looking at it how do you get it off for inspection special tools needed? Timing chain/ belt was done at 221,000 miles by local Firestone dealer then car sat for 3 years not being driven at all could they have not properly seated the lower seals? The tensioner pulley assembly looks like the original one that came with the car