// BTW, this will eventually return a string containing the token_numth token. But I'm just trying to get it to work for now.
void strsplit(const char *str, char splitchar, int token_num)
{
	char *delimeter = "\0";
	delimeter[0] = splitchar;
^^^ delimiter is a ponter that oritinally points to someplace
in read-only memory.  You can't, in most cases, write to read-only memory like that.  
When you do, either you will get runtime errors or undefined behavior
	int i;
	strcpy(str, line);
^^^ 	attempt to copy something to read-only memory.  Note that your program passed a
 string literal to this function, and all (or most) string literals reside in read-only memory

        char *token = line; /* point to the beginning of the line */
^^^ where is variable line defined?  I don't see it anywhere

	for (i = 0; *token; i++) /* loop through each character on the line */
	{
		/* search for delimiters */
		size_t len = strcspn(token, delimeter);
		token[len] = '\0';
^^^ this is identical to strtok().  You may as well have used it.

		/* print the found text: use *.* in format to specify a maximum print size */
		printf("token[%2d] = \"%s\"\n", i, token);
		 /* advance pointer by one more than the length of the found text */
		token += len + 1;
	}
}

char line[1024];

char tmpbuf[1024];
char retval[256];
 
char *strsplit(const char *str, char splitchar, int token_num)
{
	strcpy(str, tmpbuf);
 
	// fix a stupid bug
	if (tmpbuf[strlen(tmpbuf) - 1] != splitchar)
	{
		tmpbuf[strlen(tmpbuf)] = splitchar;
		tmpbuf[strlen(tmpbuf + 1)] = '\0';
	}
 
	printf("%s\n", tmpbuf);
 
	char *delimeter = "\0";
	delimeter[0] = splitchar;
	char *token = tmpbuf; /* point to the beginning of the line */
 
	int i;
	for (i = 0; *token; i++) /* loop through each character on the line */
	{
		/* search for delimiters */
		size_t len = strcspn(token, delimeter);
		token[len] = '\0';
		/* print the found text: use *.* in format to specify a maximum print size */
		printf("token[%2d] = \"%s\"\n", i, token);
		if (i == token_num)
		{
			strncpy(token, retval, (len < 256? len:256));
			retval[(len < 256? len:256)] = '\0';
			return retval;
		}
		 /* advance pointer by one more than the length of the found text */
		token += len + 1;
	}
}