I did concider using other instructions to emulate the missing instructions as you suggest,butthe problem was that the number and type of instructions that i might want to not use is variable,which adds some complications. and I will concider talking to compiler vendors such as yourself for one or two new projects which I have comming up in the next month or two.
Its a bit late for this current project as the design is in the physical layout stage and should be in production by the end of the month.
As long as its not too expensive to have a custom compiler written,prehaps there a duscount for 8052.com users:-)