how???

If you're askign for Digimon World DS jsut go back to where you fought his evil form, beat him again, and he'll give you his scan data. Then go back to your DigiFarm and DigiConvert him. There you go.

but if you are talkin about digimon world dawn or dusk you will get it after you finish the legendary tamer mission

The person above forgot to mention when you beat him at the end of Dawn/Dusk, he gives you the Scan Data of an In-Training digimon, Chicchimon.

Anyways, you can DNA Digivolve to get Chronomon Holy Mode (HM). You need to DNA Digivolve Varodurumon and Susanoomon at level 83, Friendship 100%, and friendship with Chicchimon.

Varodurumon - DNA Digivolve Silpymon and Sinduramon. Level 63, 16000 Holy Exp, 24000 Bird Exp
1. Silphymon - DNA Digivolve Gatomon and Aquilamon, level 35, 7000 Bird Exp, and 190 Speed
2. Sinduramon - DNA Kokatorimon and Akatorimon, level 34 with 7000 Bird Exp

Susanoomon - DNA either Magnamon and SuperStarmon, or Kongoumon and Yatagaramon. Level 73, 460 Spirit, and 88888 total Species Exp.
1. Magnamon - Veemon at level 40 with 10000 Holy Exp, and use the Digi-Egg of Miracles on him
2. Superstarmon - Starmon at level 41, 190 Attack, and 8800 Holy Exp
OR
3. Kongoumon - Wormmon at level 30 with 6000 Dark Exp
4. Yatagaramon - Ultimate of Falcomon