What is it that doesn't allow us to do that now?
The fact that most of these people are in the country without official knowledge; how can you monitor someone if you don't know he/she is even here? By allowing these workers to enter legally, after getting a visa, being registered and having a background check, you know who they are and where they are.
I think any guest worker program should require the worker to keep a current address on file. If the worker moves without notifying their employer or the INS, that would be grounds for revoking the visa, denying a new visa for 5 years, and immediate deportation.