1. I don’t have jerk blocks, how should I complete the prescribed reps?
Build, or buy, jerk blocks (did you really expect a different answer?). If you have a squat rack, you can do squats, presses, etc. If you have jerk blocks, you can do everything you can do on a squat rack AND do jerks (and pulls). If you have 2 sets of jerk blocks, or build enough pieces, you will also have a perfect setup for Jerk Recoveries (hint, hint).
For weightlifters, jerk blocks are mission critical. Either buy a set or make them. But the other, much less desirable answer if you absolutely do not have them right this second, is what I posted in the comments a couple of days ago: do a jerk, bring it down quickly and rack it. Wait five seconds, un-rack, jerk, repeat.
2. How do I do a snatch off the blocks from the power position?
1) Snatch from blocks (power position): work to a 3rm (drop each rep and reset quickly) – 1×3@95%, 1×3@90%
2) Snatch: 5×3@90% of 3rm from Tuesday (non-T&G, reset quickly after drop)
1) 3-Stop Snatch Pull (2 count pause at each position): 5×3@90% of 3rm from Tuesday
2) 5 SN Grip Behind-the-Neck Push Press + 3 Overhead Squats: work to a 1rm for Complex – 1×5+3@95%, 1×5+3@90%.