- Living certificate, stamped by the local PSB (cops). - A foreign expert's card (which generally requires a degree). - A health check (on arrival). - An employer that's able to employ foreign experts. (High tech should be easy enough, as long as they employ locals too). - A company that will "look after" you (flights in and out, accommodation, medical insurance, maybe food allowance).
It's not too hard. There's a lot of running around that the company needs to do for you, which could take about a month (more if they haven't done it before).
Note, you can work on an L or F visa, but risk fines and deportation. Companies will say they have "connections", so the visa doesn't matter. If they have "connections", they can get a visa.
To actually work, then you need the Z visa which is a bit more of a hassle as wisty said...