I agree with more strict enforcement on employers, however I also think that in the absence of a self-consistent immigration policy that includes a closed border, such a measure would be punitive and hypocritical.
If the government isn't going to be serious about closing the border and rationalizing our immigration policy, then punishment for employers who hire illegals should be limited to those who pay less than minimum wage, or deny benefits to undocumented workers. This caveat will focus on already illegal behavior and companies employing illegals.
Ideally speaking, a rational immigration policy, closed border, and strict and punitive enforcement of immigration laws on employers and illegals in-country would be preferred.
It brings to mind that Canada is far more discriminating and less welcoming to immigrants than we are. Even White Anglo Saxon Protestants with jobs and savings in the bank have trouble emigrating to Canada, let alone third world refugees with no education and employment offers. Then again, Canada can't absorb or employ the numbers of immigrants that we can.
As for the specifics of how the guest worker program will work, I think employers who insist on hiring an immigrant can register with the INS, who will then post employment opportunities. The employers would pay a finder's fee and work with the guest worker they end up hiring as far as covering costs goes. But there should be a number of open slots for seasonal workers, menial laborers/unskilled, who will be admitted based on economic requirements for immigrant labor defined by each state. Essentially, states would be able to set quotas with the INS for visas they need to fill gaps in employment within their state, and the parameters that the state is looking for.
There will have to be a "bond" system, for employers or states who request guest worker visas where the employer or state pays a refundable bond, refunded upon the successful completion of a visa term and the departure of the guest worker, or conversion of the guest worker's status to citizen track and permanent residency. A violation of the visa term, including conviction of a criminal act would result in forfeiture of the bond, and possibly revocation or limitations on that state's or employer's access to the system.
The bond system is used in other countries successfully. If certain states or employers feel the need to hire immigrants, the system should not be prohibitive or punitive for those who work with the system. If anything the system should grease the wheels and enable, or else we might as well not bother with the fiction of immigration, and just close our borders and revoke all immigration visas, future and pending.