eventually i got it and played with an address in the format prefix.payload.ckechsum for an uncompressed WIF key and pre.pl.01.cksum for a compressed one and that the prefix 80 results in 5 and e.g. b0 in 6 (uncompress so without 01)
uff thx...

are there alts using complete other techniques than privKey->sha256-> sha256-> checksum + to privkey -> base58encode ?