Hi Kautuk,
There is no supported way of adding autocomplete to a textbox because this would require adjusting the html which may change with UR/SPs.
I suggest that you either:
1. Use duplicate detection rules to find existing accounts (http://msdn.microsoft.com/en-us/library/gg309427.aspx) - the functionality to do those on save is coming back in the Spring '14
release (SP1).
2. Create javascript that fires on change of the name field and performs a search of existing accounts
3. If you really need an autocomplete, you can create an html web resource that has the autocomplete box and sets the account name field (which you can hide). You might check out my open source HTML library for doing this -
www.sparklexrm.com
Hope this helps,
Scott
Scott Durow
Blog www.develop1.net
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