On an ANSI keyboard, a single function key could toggle the numpad's 1-9 keys into F1-F9 keys, and have the additional 3 on top be F10-F12. That might give you an experience similar to the Omnikey's side F keys, as long as you're OK with having them on the right side. Might work better if the arrow keys and nav keys above it were removed so that the Numpad would be quicker to reach, since the Num Lock key makes them redundant anyway.
On an ANSI keyboard, a single function key could toggle the numpad's 1-9 keys into F1-F9 keys, and have the additional 3 on top be F10-F12. That might give you an experience similar to the Omnikey's side F keys, as long as you're OK with having them on the right side. Might work better if the arrow keys and nav keys above it were removed so that the Numpad would be quicker to reach, since the Num Lock key makes them redundant anyway.