I don't know anything about doing without the H2SO4 catalyst but...

It is normally used as concentrated sulfuric acid (e.g. 98% or so).  You don't want any H2O if you can help it, as this drives the reaction towards reactants, not products.  You only need a few drops.  Besides being acid, it helps by removing product H2O with its dehydrating action.

You can likely find concentrated H2SO4 in the hardware store, as drain cleaner.  I know the 'usual' drain cleaner is the completely-opposite-pH NaOH, but H2SO4 is also sold.  It was once offered to me when I told the salesman that the usual wasn't strong enough for my job.  The stuff was horribly full of impurities, being dark brown instead of colorless, probably Fe contamination.  The hardware store aisle in the grocery store probably won't have it, so you'll need to try a real hardware store.

Chemicals needed for methyl salicylate synthesis:  Salicylic Acid, Sulfuric Acid, Methanol

Make Salicyclic Acid:
50ml 70% IPA (Isopropyl Alcohol)
18.1g Aspirin (325mg Acetylsalicylic Acid per tablet = 16,250mg / 16.25g)

Warmed IPA on hotplate (lowest setting)
Dissolved Aspirin tablets in IPA until completely disintegrated
Gravity Filtered solution using coffee filter. - Washed with excess IPA
Added 50ml COLD Water to beaker with filtered material.
Added 4 ice cubes and Acetylsalicylic Acid began to percipitate from solution.  (about 3 minutes elapsed time)
Collected "mush" in evap dish.  Placed in Oven @ 200F until dry.


Collected Acetylsalicylic Acid
100ml HCl - 31.45% - Muratic Acid (Hardware Store)

Combine Acetylsalicylic Acid & Hydrochloric Acid in beaker with stirring bar on hotplate with vigorous stirring (you can do it by hand)
This needs to be refluxed.. You can do it by covering the beaker with non-wooden cutting board and ice or using a relux column.
Raised reactant temperature to 50-60C and left react for 30 minutes - Reaction was obvious as mixture greatly thickened.  

Dry and you now have Salicylic Acid.

Combine the Methanol, Salicylic Acid and a few catalyic drops of Sulfuric acid and reflux for 40 minutes.  You have a very nice smelling oil of wintergreen.  At that point you can separate and purify.. I didn't.

Home Depot? What do they have there?

Home Depot? What do they have there?

It's a giant hardware sell that sells everything needed to build and maintain a house and then some. I know it's located in the States. I don't know about it's international existence and where most Home Depots. I know there are 2 within 25 miles of me.