Step 1: Set a side A LOT of time
Step 2: Pull out a strand
Step 3: Grab said strand at the base with your tweezers
Step 4: Slide tweezers into substrate and gently release
Step 5: Scramble to catch floating HC that the substrate didn't really get a hold of before you opened your tweezers and replant it
If you have any flea markets in your area there are some tool guys out there with Indian and Pakistani stainless tools. Although I have yet to find such a dealer in my area (haven't been to the markets in a while) it's always another source... The Bay Area have several flea markets that carry tools of this nature. Mostly scissors and forceps but some can be used for our use.
Main thing is to get a pare that are long and thin to keep from pushing the substrate out of the planting zone.
Personally i have never planted HC. I use the same technique planting bacopa and other stems with a pare of 18" forceps.
Also check out eBay. I got some nice 11-12" curved tip DeBakey vascular forceps and curved Metzenbaum scissors, real surgical instruments, for a pretty good price ... don't recall that price exactly, but I think two of the DeBakey's ran me $50 and the Metz's $20-25 ...
I just got a pair of ADA pincettes recently. They have a very fine tip and are long. I love mine. I'm not one of those people who go ADA for every single piece of equipment out there, but I like these.