First of all you need to compile HTND testnet versions from source, as Tonto won't be building them as they may need to be updated more often depending how many bugs arise in testnet testing.
Required for building HTND:
How to clone the github repository and build
git clone https://github.com/HoosatNetwork/HTND.git
cd HTND
git checkout dagknight # can be changed to whatever branch name
go install -tags "deadlock pebblegozstd" . ./cmd/...
To update
cd HTND
git pull
go install -tags "deadlock pebblegozstd" . ./cmd/...
To run
HTND --utxoindex --testnet -a mainnet-node-1.hoosat.fi --allow-submit-block-when-not-synced
Generate testnet address with genkeypair or use htnwallet with --testnet flags
genkeypair --testnet
Then you can start mining with htnminer or download Hoominer or Hoo_XPU miners depending on your needs, but htnminer is enough for testnet mining.
htnminer --testnet --miningaddr=hoosattest:blaablaalbaadagknightblaa --threads 1
So if you find any issues, please report them in HTND Github issues