It's a bit unclear what you mean with "the DNS method". For both verification methods DNS is involved.
Method 1 - Most basic, this is not really a verification
Change the nameservers for your domain to ns1.sedoparking.com and ns2.sedoparking.com. This may work, but when there's another member already listing your domain on Sedo, you have to use method 2.
Method 2 - Self-verification using your 'Domain Ownership Verification ID'
Keep your registrar nameservers unchanged, but
add a TXT and/or CNAME record for your domain. For this, first visit
https://sedo.com/member/account_setting.php and find your personal "Domain Ownership Verification ID". Now go to the DNS settings at your registrar and add one of the following DNS records for your domain. You may even add them both if you like.
Let's say
example.com is the domain you want to list at Sedo. You will then add the following records in DNS:
example.com. TXT sedo-verification-id
-- and / or --
sedo-verification-id.example.com. CNAME verify.sedo.com.
It may take some time, but eventually you will see that your account has been verified by Sedo automatically. If you still have problems, you may contact Sedo Support.
Here's a video created by Sedo on this topic. Good luck.