Sorry for the necro but I found that there were no sufficient answers to be found here to my liking.
Like the other posters said, if you want to dig using dfhack, tiletypes is your best bet.
Once you are able to get tiletypes running in the console, you are given 3 options:
1. Filter - Ignore this for the time being. It is unnecessary
2. Paint - We'll get into this
3. Brush - Brush Size, to be more precise.
Changing Paint syntax is as follows: paint [parameter] [parameter definition].
To find out what parameters exist, type in [help]. This will list what can go into the [parameter] bracket in the above syntax format.
To find out what each parameter does, type in [help][parameter_name].
Examples:
1. paint material stone: this changes the material to a stone material. Because this is unspecified, the stone used will reflect on your embark. If you embark on a map with lots of limestone, this will default to limestone or whatever else is on your map.
2. paint stone sandstone: this changes the material to be specific. In this case, the specific type of stone to be used is sandstone.
3. help stone: this gives a short description as to what the [stone] parameter does.
3. Brush: the size of the brush. The syntax is as follows: range [x-length] [y-length] [z-length]. However, you do not need to enter all 3 parameters to work.
By default, entering only [x-length] and [y-length] parameters will give a [z-length] of 1. Giving only 1 parameter, the [x-length] parameter, or less will prompt the user to enter in all 3 parameters.
Do keep in mind that all commands entered through tiletypes will start from the lower north-west cornet. So for multiple z-levels, paint starting from the lowest level.
Also keep in mind that when specifying a stone to use, the name must match what is written in the raw files. Do not use [stone:limestone]. Do use [limestone]. What are raw files? Raw files refer to the files found within folder named "raw" in the Dwarf Fortress directory.
There are 2 types of "digging" using dfhack. One is used to remove the block, another is used to remove the floor above.
To remove the block below, simply use [paint] [shape] [floor] along with whatever material you want.
To remove the floor above, use empty air blocks as follows:
1. paint [shape] [empty]
2. paint [material] [air]
This will create an open space.
I hope this will be good future reference.