I am working on a ridculous project to bring the cassette-in interfrace from the early 8-bit A2s to the IIGS. I have the hardware worked up (I think so anyway) but on the software side of things I have hit a major wall. My original plan was to trim the tape read code as much as possible and enter it in by hand, however this doesn't seem to be a very good idea since the minimum code required is still somewhere in the neighborhood of 160 bytes. I then decided to use the entire tape in routine found in the earlier A2s and place it in the same address locations on the IIGS, but this proved difficult because I was trying to use the mini-assembler and manually enter the code, but I could never get it to work, I don't know if it was because I didn't have everything entered, if I entered a part in incorrectly, or if I have any issue with my hardware.
So here is what I have and what I am trying to do:
1) I have the machine language and assembly code that I want to enter that I have taken from the Apple II ROM listing
2) I know where I want the code to be entered.
3) I do not know if I have all of the code required so I would like to know the process, so I don't have to keep coming back and asking people for additional help
I want to be able to write snippets of code to various blocks of memory. I want to eventually have a bootable disk that I could put in and load the memory to the various location, but for now I would settle for how to enter the data using serial, using an ASCII file (I assume the IIGS can use ASCII files) or using pokes from BASIC. I am well out of my depth here and I can't find the information that I am looking for. At the moment I don't really care exactly how everything works on the software side (I do have the assembly lines book and eventually want to learn the how), I just want to be able to put specific code in specific locations and I cannot seem to find how to do this.
Of course if anyone wants to write me a bootable disk image I won't complain. 
The easiest way would be to enter all the snippets of code into source code and use an assembler to create the binary code. This allows you to make changes a lot easier.
To use the mini-assembler on a IIGS, type "!" at the monitor prompt.
Then the starting address of where to put the code, followed by the first mnemonic. You will want to start at a low address first (like $2000).
Then each successive line of code starts with a space, then the mnemonic.
i.e.
*!2000:lda #0
! sta $6
! lda #21
! sta $7
!(press ENTER to exit the mini-assembler)
Entering your code in low memory makes it easier to test. You can always move it elsewhere afterwards.
You can also set up the ampersand (&) function to call the cassette LOAD and SAVE calls and can be saved anywhere. Putting the code in the Language Card would mean your code would not work with Prodos.