Not sure if this is what you're looking for. To get the Raw Transaction code using MEW Offline, all you need to do is
click the "Generate Transaction" button, it will show both "Raw Transaction" and "Signed Transaction".
(see step 4)What's steps have you done already? Since you didn't mention, I did a sample offline transaction process just for you to see:
1. You go online, and "Generate Information" which are the "Gas Price" and "Nonce" using your "FROM" address
- fill out FROM address
- click "Generate Information" button
- save a copy of the "Gas Price" and "Nonce"
2. Go on your Offline computer (MEW Send Offline page) and fill out all the information needed, you'll input the "Gas Price" and "Nonce" that you generated earlier. Don't forget to double/triple check all the information.
3. Unlock your wallet using your Private Key - Select Private key > Enter Private Key - click "Unlock" button
4. "Generate Transaction" button, "Raw Transaction" field and "Signed Transaction Field" will show up after unlocking the wallet. CHECK again all the details that you filled out earlier. If you're done, click "Generate Transaction" button. After click, the "Raw Transaction" data and "Signed Transaction" data will show up. Copy the "Signed Transaction" and proceed to step 5
5. You now need to go in your Online computer
- MEW Send Offline page
- Scroll dwon
- Paste your "Signed Transaction" that you generated and copied earlier
- click "Send Transaction"
Congrats! You're done.
You can check MEW's official post (can be seen on Knowledge Base):
How To Make An Offline TransactionPS. Address and Private Key used were only for test purposes. The wallet was newly generated for this.