If it is not possible to use geodatabase aliases (see Geodatabase alias), then you may define aliases in the ArcMap document itself.
Anyway there is a significant tradeoff when defining aliases in the ArcMap document: You must do this again in every map document you use. Therefore there is considerable potential for generating a lot of redundant alias definitions which may cause a lot of additional time to maintain.
WebOffice 10 R3 is able to use these alias definitions. Therefore, if you use geodatabase or ArcMap field alias definitions, you do not need to provide any field alias configuration in the WebOffice 10 R3 project at all. This makes creation and maintenance of your WebOffice 10 R3 projects easier and more efficient.

Set ArcMap aliases in Layer Properties - Fields tab