You cannot key in synthetic instructions just as you do with regular '41 commands. These commands are, well ...synthetic. ;-)
Which essentially means that you are dealing with byte sequences that usually cannot be entered at all. The regular 41 operating system prevents the user from doing so.
Here's an example: STO N is byte code 91 76. You can press [STO], but there is no way to have it followed by an N. However, you can enter RCL IND 17 followed by LastX. In hexadecimal byte notation, this is 90 91 76. Now you just have to remove the first byte (90) somehow (e.g. with the fabulous "byte grabber"). This leaves 91 76 - et voilà, there is your STO N. It was synthesized from two other commands.
As you can see, you will need at least two things: first, a HP41 byte table (available on the internet), and then a means to remove single bytes, e.g. the mentioned byte grabber. You should find some instructions on this site on how to make one.
You may also completely ignore synthetic programming. Using registers M, N and O in some programs often simply is a way to acquire a set of temporary registers. M, N, O and partially P usually hold the contents of the 41's alpha register. So a simple CLA clears them all at once, and if a program does not use the alpha register, you get three or four registers for free, even with SIZE 000 set. Which is very handy but not the only possible way. Simply replace these registers with regular numbered ones, and you are done. On the other hand, if you really come across a synthetic program that uses these registers in a more sophisticated way, or does even things that cannot be done with standard programming, you will have to dig much deeper into the world of synthetic programming. Which means: get a book and take your time.
Dieter
