This article applies for weDict/weDict Pro 1.3 or above, iPhone OS 2.0 or above, tested on 3.0.
Prerequisites:
Jailbreak (PWN) if you use weDict free version. If you use weDictPro, you don't have to jailbreak it.
How to use Stardict Dictionaries for weDict (in this case say we use longman for example, all others are similar)
1. download the dictionary from stardict stardict-longman-2.4.2.tar.bz2
2. extract the tarball and find the file longman.dict.dz
3. rename longman.dict.dz to longman.dict.gz or .zip as it is in fact a zip file
4. get the file longman.dict
5. copy longman.dict and longman.idx/longman.ifo to folder /private/var/mobile/Applications/BFEA9FDA-0903-4321-9A7D-1A0DA030FF21/Documents
Note: the RED+BOLD string may vary on different devices, please dig yourself for weDict folder.
6. to avoid permission issue, change their permission settings to 755 (-rwxr-x-r-x)
7. launch weDict and hit the configuration button, now you should be able to see the new longman dictionary listed
If not listed, please make sure to quit/terminate weDict by pressing Home for 5 seconds. Of course you can use Terminal if you want. Enjoy!
Difference between weDict and weDictPro:
For weDictPro users, you can use the built-in FTP service (ftp://ip:1234) to upload the dictionaries, also you can download from default source and download from a http URL (can be LAN but pay attention to format). However, we can still use do the job that Pro does for paid users manually and enjoy the same.
Officeial FAQ: http://app.weiphone.com/wedict/index.html
Blog Post:
Blog post in Chinese can be found here: How to use Stardict dictionaries for weDict/weDictPro on iPhone/iPod Touch
Notes: If you upgrade weDict/weDictPro, for example from 1.2 to 1.3 all custom added dictionaries will be kept. If you delete it and reinstall, make sure to backup the dictionaries in Documents folder.