Definitely do-able in steel Most of the plunging Ive done has been in various steel castings for deep pockets or profile roughing in materials like 317L which is highly abusive to most cutting tools . To plunge in steel you'd need the right tool for the job (real plunge mill) I wouldn't use an end mill to plunge anything other that maybe a free machining steel , and even then I'd go another route
If your cutting loads of steel then you might be best off buying insert mills , the initial cost is high but over time the savings is there and the tool pays for itself quickly . I've used a lot of sanvik over the years and their cutter module is incredible CuttingData Module - Milling
The speeds and feeds this thing calculates can be down right scary until a guy gets used to it
The high speed , high efficiency toolpaths are probably the best choice for general machining steel work .. Theres a lot of air cutting with high speed tool paths which is why I find them worthless in aluminum , but for steel they can be ideal at times .