Mr. Neil: I am sorry to have angered you somehow. However, I mut clarify that I had read the manual, the place you referenced, and many other resources for hours, and had not fixed the issue. The problem had nothing to do with syntax (I had tried the correct syntax as well, and many other syntaxes; In fact, one of the syntaxes I listed is a valid alternative). The problem lied in my assumption that 89s8252 had defined the sbit P3_2 already, which apparently it had not. When I manually assigned it to the appropriate port using the sbit statement, then used a define statement to set the alias button to that port (exactly as I listed above), as suggested by the very helpful mr. purohit, everything worked brilliantly.
I'm sure this is probably documented somewhere, but I cannot find such documentation anywhere in your link, the man files that come with SDCC, or any of an innumerable SDCC reference sites I came across last night.
When all ducumentation resources are exhausted, what recourse is there but to ask those who are knowledgable?